Category Archives: Furthering Freshwater Fishkeeping

Premixed foods for plecos (Loricariids) and other rasping fishes.

Choosing fish foods can be very confusing, there are many products on the market all with various claims. The majority of fish diets are formulated based on the nutrition for food fishes, these diets have an aim to have a high growth rate while minimizing costs, efficiency would be the best term. The aim of the ornamental aquarist is far from that, we want a long lived healthy fish with good coloration. The nutritional composition requirements are differ between the two aims (Vucko et al., 2017). This has resulted in many diets not catering for the aim of the fishkeeper and no where is this more obvious then diets aimed at plecos, Loricariids.

The majority of Loricariids are algivores or detritivores, but there is a diversity of dietary niches (Lujan et al., 2015). Contrastingly many products labelled as pleco or algae wafers/pellets contain little to no algae but higher proportions of fish meal (Vucko et al., 2017). The majority of popular Loricariids are along the lines of algivory or feed on various volumes so this should be a focus for the aquarist. Additionally I have yet to see fish ever recorded in the gut of any Loricariid.

Catering for Algivores/detritivores.

I have written quite a bit about this niche and therefore I recommend reading this article here which covers details into algivory, detritivory and wood eating.

These fishes are the most difficult to cater for giving there isn’t quite the selection of algaes available in any diet. Some of them can be difficult for the fish to take to so hence I find Repashy soilent green good and can then be bulked out with even more algae’s.

Catering for Carnivores.

I am not really discussing carnivores so much in this article as there are many diets that cater for them and in recent years with the focus into invertebrates it is only improving. Still, many diets are very high in fish meals, something Loricariids do not consume and nutritionally these do not compare. Not just can fish meals be different nutritionally, the nutrients can be difficult to access (Žák et al., 2022).

There is a little diversity of carnivory within Loricariidae but we don’t entirely know to what extent. I have written this article for mollusc specialists and although diverse in diets this for dwell in and around the substrate.

The great thing for carnivores is the diversity of frozen foods we have available within the hobby and even fishmongers. Although keep aware for the enzyme thiaminase (in mussels and some fishes) and limit the frequency these are fed to your fishes.

Other niches and specialization.

Fungi hyphae are found in the diets of Panaque, Panaqolus and the Hypostomus cochliodon group and are likely digested, mushrooms or mycoproteins would be the closest to replicating this (Lujan et al., 2011). Sadly most diets don’t contain these. It would be interesting to feed wood that has many of these but usually by the point they have obvious hyphae they are almost entirely broken down.

While Hypancistrus are largely algivores, there is evidence a few of them feed on seeds, read about Hypancistrus here. The exception being Hypancistrus vandragti who seems a little more carnivorous in comparison (Lujan & Armbruster, 2011).

Will they eat it?

Something few consider is that just because a diet might be amazing with ingredients they might not eat it. So there are a range of ingredients such as some herbs used entirely to encourage fishes to eat a diet. This has been the issue I’ve found with some that have great ingredients Repashy super green for example.

Premade diets and their ingredients

Premade diets unlike if you were to make anything yourself entirely will have a reasonable range of nutrients. They are best more as a basis to work from for a more well rounded diet.

From these tables it is easy to understand the varying suitability of different diets to different species and genera. The colour coding is only to give an idea as many ingredients have multiple purposes e.g. fish meal can be a binding agent as well as for nutrition.

Ingredients are ordered in quantity so the top of the list contributes the most.

The hidden issue with premade diets

There is a hidden issue, as you look across the table how similar are many of these diets? Many fishkeepers will buy a range of different products in the aim of diversity of nutrition and ingredients. If so many of the ingredients and the orders are similar this means that there is little diversity, the exception would be there the major ingredients are very different.

Products sold for plecos

Company	Repashy
Product	Soilent Green	Super Green	Bottom scratcher	Morning wood
Dietary Niche	Algivory	Algivory	Carnivory	Xylovory
Summary	Fishes tend to prefer this diet. Contains mostly algae but has a some animal meals but can be bulked out with more algae’s.	Contains no animal products. Fish seem less keen on it. High in algae’s.	Contains a diversity of invertebrates. Shouldn’t be fed as the only diet for non-carnivores as can lead to bloat e.g. Hypancistrus.	No Loricariids digest wood, cellulose is the main ingredient.
Composition (%):
Protein	40	35	45	20
Fat	8	8	10	3
Fibre	8	8	12	50
Moisture	8	8	8	8
Ash	12	9	11	15
Ingredients
	Spirulina Algae, Algae Meal (Chlorella), Krill Meal, Pea Protein Isolate, Squid Meal, Rice Protein Concentrate, Fish Meal, Alfalfa Leaf Meal, Dried Brewer’s Yeast, Coconut Meal, Stabilized Rice Bran, Flax Seed Meal, Schizochytrium Algae, Dried Seaweed Meal, Lecithin, Dried Kelp, Locust Bean Gum, Potassium Citrate, Taurine, Stinging Nettle, Garlic, RoseHips, Hibiscus Flower, Calendula Flower, Marigold Flower, Paprika, Turmeric, Salt, Calcium Propionate and Potassium Sorbate (as preservatives), Magnesium Amino Acid Chelate, Zinc Methionine Hydroxy Analogue Chelate, Manganese Methionine Hydroxy Analogue Chelate, Copper Methionine Hydroxy Analogue Chelate, Selenium Yeast. Vitamins: (Vitamin A Supplement, Vitamin D Supplement, Choline Chloride, Calcium L-Ascorbyl-2-Monophosphate, Vitamin E Supplement, Niacin, Beta Carotene, Pantothenic Acid, Riboflavin, Pyridoxine Hydrochloride, Thiamine Mononitrate, Folic Acid, Biotin, Vitamin B-12 Supplement, Menadione Sodium Bisulfite Complex).	Spirulina Algae, Algae Meal (Chlorella), Pea Protein Isolate, Rice Protein Concentrate, Alfalfa Leaf Powder, Stabalized Rice Bran, Dandelion Powder, Dried Brewer’s Yeast, Coconut Meal, Ground Flaxseed, Schizochytrium Algae, Dried Seaweed Meal, Dried Kelp, Locust Bean Gum, Lecithin, Potassium Citrate, Taurine, Stinging Nettle, Garlic, RoseHips, Hibiscus Flower, Calendula Flower, Marigold Flower, Paprika, Turmeric, Calcium Propionate and Potassium Sorbate (as preservatives), Magnesium Amino Acid Chelate, Zinc Methionine Hydroxy Analogue Chelate, Manganese Methionine Hydroxy Analogue Chelate, Copper Methionine Hydroxy Analogue Chelate, Selenium Yeast. Vitamins: (Vitamin A Supplement, Vitamin D Supplement, Choline Chloride, Calcium L-Ascorbyl-2- Monophosphate, Vitamin E Supplement, Niacin, Beta Carotene, Pantothenic Acid, Riboflavin, Pyridoxine Hydrochloride, Thiamine Mononitrate, Folic Acid, Biotin, Vitamin B-12 Supplement, Menadione Sodium Bisulfite Complex).	Krill Meal, Insect Meal, Mussel Meal, Squid Meal, Dried Brewer’s Yeast, Dried Seaweed Meal, Lecithin, Dried Kelp, Locust Bean Gum, Potassium Citrate, Taurine, Watermelon, RoseHips, Hibiscus Flower, Calendula Flower, Marigold Flower, Paprika, Turmeric, Stinging Nettle, Garlic, Salt, Calcium Propionate and Potassium Sorbate (as preservatives), Magnesium Amino Acid Chelate, Zinc Methionine Hydroxy Analogue Chelate, Manganese Methionine Hydroxy Analogue Chelate, Copper Methionine Hydroxy Analogue Chelate, Selenium Yeast. Vitamins: (Vitamin A Supplement, Vitamin D3 Supplement, Choline Chloride, Calcium L-Ascorbyl-2-Monophosphate, Vitamin E Supplement, Niacin, Beta Carotene, Pantothenic Acid, Riboflavin, Pyridoxine Hydrochloride, Thiamine Mononitrate, Folic Acid, Biotin, Vitamin B-12 Supplement, Menadione Sodium Bisulfite Complex).	Cellulose Powder, Dried Seaweed Meal, Alfalfa Leaf Meal, Spirulina Algae, Rice Protein Concentrate, Pea Protein Isolate, Stabilized Rice Bran, Dried Brewer’s Yeast, Dried Kelp, Stinging Nettle, Locust Bean Gum, Calcium Carbonate, Potassium Citrate, Malic Acid, Taurine, Garlic, Watermelon, RoseHips, Hibiscus Flower, Calendula Flower, Marigold Flower, Paprika, Turmeric, Salt, Calcium Propionate and Potassium Sorbate (as preservatives), Magnesium Amino Acid Chelate, Zinc Methionine Hydroxy Analogue Chelate, Manganese Methionine Hydroxy Analogue Chelate, Copper Methionine Hydroxy Analogue Chelate, Selenium Yeast. Vitamins: (Vitamin A Supplement, Vitamin D Supplement, Choline Chloride, Calcium L-Ascorbyl-2-Monophosphate, Vitamin E Supplement, Niacin, Beta Carotene, Pantothenic Acid, Riboflavin, Pyridoxine Hydrochloride, Thiamine Mononitrate, Folic Acid, Biotin, Vitamin B-12 Supplement, Menadione Sodium Bisulfite Complex).

Repashy products, coloured by type of product; algae (Dark green), Plant Matter (blue), cereal (Orange), animal matter (red), vitamins (pink), not highlighted might have other purposes such as binding agents or other nutrition.

Repashy unlike the other brands is a gel diet, this means other products such as algae powders can be added in. This means for any of them you can increase the algal composition or add ingredients such as basil.

Company	Fluval		AquaCare
Product	Bug Bites Pleco Sticks	Bug Bites Pleco Crisps	Spirulina Sinking Wafers	Oak
Dietary Niche	Carnivore	Omnivore/cereals	Omnivore	Omnivore/cereals
Summary	A reasonable amount of insects so more ideal then those with more fish meals for carnivores.	A smaller amount of insect meals and contains a wider range of cereals.	Mostly fish meal with a lot of cereals, little algae.	Loricariids cannot digest wood/cellulose nor is it used for digestion. Mostly wheat, which will have limited nutrition and a high amount of fish meal.
Composition (%):
Protein	32	43.5	43.7	38.3
Fat	12	4	5.7	3.7
Fibre	6	3	3	3.2
Moisture	?	?	7.1	9
Ash	9	5	10.5	13.4
Ingredients
	Black soldier fly larvae (30%), salmon (22%), wheat, peas, potato, dicalcium phosphate, alfalfa nutrient concentrate, calcium carbonate, calendula, rosemary.	Insect Meal (Mealworm Meal 15%, Black Soldier Fly Larvae 10%), Wheat flour, Wheat Gluten, Wheat germ, Alfalfa, Spirulina, Fish Protein Hydrolyzed, Kelp (5%), Shrimp Protein Hydrolyzed, Spinach (5%), Activated Charcoal.	Fish meal, Wheat, Wheat Gluten, Mycoprotein, Shrimp, Spirulina, Alfa-Alfa, Salmon Oil, Wheat germ, Spinach, Vitamins, Minerals	Wheat, Herring Meal, Wheatgerm, Spirulina, Alfalfa, Kelp, Oak Bark, Zeolite, Minerals, Vitamins

Coloured by type of product; algae (Dark green), Plant Matter (blue), cereal (Orange), animal matter (red), vitamins and minerals (pink), not highlighted might have other purposes such as binding agents or other nutrition.

Company	Hikari	Dr Bassler		Vitalis
Product	Algae Wafers	Green	Regular	Pleco Pellets
Dietary Niche	Omnivore	Omnivore	Omnivore	Omnivore
Summary	Not ideal. Contains a lot of fish meal and cereals. A general diet that targets no species.	Very high in cereals and fish meals. Too few algaes to cater for an algivore.	Pretty much the same as the green diet. A lot of fish meal and cereals.	Not ideal. A very general diet that doesn’t cater for any species. Mostly contains fish.
Composition (%):
Protein	33	57	54	39.4
Fat	4	18	16	7
Fibre	3	2	4	1.5
Moisture	10	?	6	25
Ash	17	10	10	17.3
Ingredients
	Fish meal, wheat flour, wheat germ meal, cassava starch, dried bakery product, dried seaweed meal, alfalfa nutrient concentrate dehydrated, dehydrated alfalfa meal, brewers dried yeast, soybean meal, fish oil, krill meal, spirulina, garlic.	Cereals, fish and fish derivatives, derivatives of vegetable origin, Chlorella pyrenoidosa (5 %), Moringa oleifera (5 %), molluscs and crustaceans, yeast, minerals Additives: Vitamins: E672 Vitamin A 7,500 IE/kg, E671 Vitamin D3 2,500 IE/kg , E300 Vitamin C 500 mg/kg, E307 Vitamin E 260 mg/kg, Magnesium 400 mg/kg, Iron 300 mg/kg, Omega-3 fatty acids 50 mg/g, Vitamin B3 7.5 mg/kg, Chlorophyll 2 mg/kg, Folic acid 2 mg/kg, Selenium 1 mg/kg, Iodine 0.02 mg/kg	Fish and fish derivatives, cereals, molluscs and crustaceans, derivatives of vegetable origin, yeast, minerals Additives: Vitamins: E672 vitamin A 7500 IU/kg, E671 vitamin D3 2500 IU/kg, E300 vitamin C 500 mg/kg, E307 vitamin E 260 mg/kg	Fish and Fish Derivatives, Derivatives of Vegetable Origin, Algae, Oils and Fats, Minerals, Molluscs and Crustaceans.

Coloured by type of product; algae (Dark green), Plant Matter (blue), cereal (Orange), animal matter (red), vitamins (pink), not highlighted might have other purposes such as binding agents or other nutrition.

Company	Oase	Tetra	New Life Spectrum	Fish Science
Product	Organix Veggievore Tabs	Spirulina Wafers	Algae Max	Algae wafers
Dietary Niche	Carnivore	Herbivore	Algivore	Omnivore
Summary	A lot of fish/shrimp meals. Only a small amount of krill.	Plant focused but lacks a lot of algaes.	Beware some have higher fish meal volumes. Otherwise a great range of algaes.	Would benefit from more algaes, the use of mycoproteins is interesting but still a large amount of cereals and fish meal.
Composition (%):
Protein	35	28	34	42
Fat	13	6	8	7.5
Fibre	1	5	8	2.2
Moisture	?	9	10	10
Ash	9	?	?	8.5
Ingredients
	Whole Salmon, Whole Shrimp, Wheat Flour, Kelp, Whole Herring, Wheat Germ, Vitamins and Minerals.	Cereals, Vegetable protein extracts, Derivatives of vegetable origin, Yeasts, Oils and fats, Algae (Ascophyllum Nodosum 3,0%, Spirulina 0,9 %), Minerals. Vitamins: Vitamin D3 1810 IU/kg. Trace elements: Manganese (manganese (II) sulphate, monohydrate) 81 mg/kg, Zinc (zinc sulphate, monohydrate) 48 mg/kg, Iron (iron(II) sulphate, monohydrate) 32 mg/kg. Colourants, Preservatives, Antioxidants.	Seaweed (Ulva latuca, Undaria pinnatafida, Eucheuma cottonii, Eucheuma spinosum, Chondrus crispus, Porphyra umbilicus), Krill (Euphasia superba), Squid (Dosidicus gigas), Whole Wheat Flour, Kelp, Spirulina, Fish (Brevoortia tyrannus), Fish Oil, Garlic, Ginger, Astaxanthin, Marigold, Bentonite Clay, Sea Salt, Vitamin A Acetate,Vitamin D Supplement,Vitamin E Supplement, Vitamin B12 Supplement,Niacin, Folic Acid, Biotin, Thiamine Hydrochloride, Riboflavin Supplement, Pyridoxine Hydrochloride, Calcium Pantothenate, L-Ascorbyl-2-Polyphosphate (Vitamin C), Choline, Chloride, Ethylenediamine Dihydroiodide, Cobalt Sulfate, Ferrous Sulfate, Manganese Sulfate, Tocopherols (a preservative).	Algae (Spirulina & Kelp 15%), Mycoprotein, Cereals, Herring meal, Vegetable protein extracts, Insect meal, Vegetables (Cucumber, Spinach), Molluscs and crustaceans, Yeast, Salmon oil and Garlic.

References:

Lujan, N. K., & Armbruster, J. W. (2011). Two new genera and species of Ancistrini (Siluriformes: Loricariidae) from the western Guiana Shield. Copeia, 2011(2), 216-225.

Lujan, N. K., German, D. P., & Winemiller, K. O. (2011). Do wood‐grazing fishes partition their niche?: morphological and isotopic evidence for trophic segregation in Neotropical Loricariidae. Functional Ecology, 25(6), 1327-1338.

Lujan, N. K., Winemiller, K. O., & Armbruster, J. W. (2012). Trophic diversity in the evolution and community assembly of loricariid catfishes. BMC Evolutionary Biology, 12, 1-13.

Vucko, M. J., Cole, A. J., Moorhead, J. A., Pit, J., & de Nys, R. (2017). The freshwater macroalga Oedogonium intermedium can meet the nutritional requirements of the herbivorous fish Ancistrus cirrhosus. Algal research, 27, 21-31.

Žák, J., Roy, K., Dyková, I., Mráz, J., & Reichard, M. (2022). Starter feed for carnivorous species as a practical replacement of bloodworms for a vertebrate model organism in ageing, the turquoise killifish Nothobranchius furzeri. Journal of Fish Biology, 100(4), 894-908.

Company
Product
Dietary Niche
Summary
Composition (%):
Protein
Fat
Fibre
Moisture
Ash
Ingredients

South America’s Electric Fishes: Gymnotiformes. A Guide for the Aquarist.

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There are few fishes that really catch the eye as much as the order of true knifefishes, Gymnotiformes. Sometimes confused with some Asian and African species from the group Notopteridae which is within the family Osteoglossiformes, also within that group is the arowana. Gymnotiformes are restricted to South America with the closest relatives being Siluriforme (catfishes) and the tetras (Characiformes) both groups who have a much wider distribution.

Figure 1: Phylogeny of Loricariidae according to molecular information (Tagliacollo et al., 2016): Tagliacollo, V. A., Bernt, M. J., Craig, J. M., Oliveira, C., & Albert, J. S. (2016). Model-based total evidence phylogeny of Neotropical electric knifefishes (Teleostei, Gymnotiformes). *Molecular phylogenetics and evolution*, 95, 20-33.

Gymnotiforme contains 6 families, 36 genera and 272 species (Fricke et al., 2024). Of these species only one is a frequent import, Apternotus albifrons with the common name black ghost knifefish. Other species do appear in the trade but much less frequently otherwise this article would be more specific.

Morphology

The order is generally identified by an eel (anguilliform) shaped body, a large anal fin that extends across the majority of the fishes abdomen, no dorsal/adipose/pelvic fins and; a caudal fin might be present but reduced (Tagliacollo et al., 2016).

The largest Gymnotiformes are in the genus Electrophorus, electric eels of which comprises 4 species, with evidence of individuals reaching over 120cm TL (de Santana et al., 2019). While the smallest might be Hypopygus minissimus at 6.4cm SL (de Santana & Crampton, 2011).

The largest amount of diversity of this family would be in the head shape, there are many with shorter heads and extremely gape limited, others with elongated jaws, some with wide jaws and quite a few with a long snout like mouth. This likely reflects their diet, while all are carnivores there is a wide range of different prey various genera will specialize in (Albert & Crampton, 2005; Ford et al., 2022).

Colouration is extremely variable although they lack any vivid colours the markings differ based likely on the environment. My personal favorite’s for colouration are the various striped members of the genus Gymnotus.

The complexity of dietary specialization

As mentioned earlier Gymnotiformes display a wide diversity of jaw and mouth shapes, some are likely more generalists and others much more specialized. A large number of genus that occur on the rare occasion tend to be these specialists.

Gymnotiformes are all carnivores and many invertivores/insectivores (Gonçalves-Silva et al., 2022; Giora et al., 2014). Some feed on particularly small food items for their relative body size. Lundberg & Mago-Leccia (1986) displayed many species feeding exclusively on plankton regardless of their body size of 8-14cm SL in some of these species. This planktivorous diet is found in many of these long nosed and gape limited species (Giora et al., 2014; Lundberg & Mago-Leccia, 1986). These species simply cannot feed on larger food items and seems to display preferences additionally on the food item. I can only recommend for these trying many different frozen and live foods in a tank with nothing that can compete but even if feeding they can be a challenge and I do not recommend. Feeding these species takes time and requires space for culturing live food, they are probably best species only.

There are genera that do work within captivity although very few. Apternotus albifrons and A. leptorhynchus the brown and black ghost knifefish, not to be confused with a Notopteridae the brown knifefish, Xenomystus nigri from Africa. These have larger mouths that extend so can even feed on tetra but due to their adult size of 30cm SL (Mucha et al., 2021) but in the aquarium some suggest 50cm. This makes them a bit of an undertaking, so the social X. nigri might be a better choice at about 11-15cm SL (Golubtsov & Darkov, 2008). X. nigri has a more extreme arched back, solid grey/black/brown colouring and the anal fin connects directly to the caudal fin. Gymnotus is the other appropriate genus to the aquarium, it is variable in size from around 15cm for Gymnotus javari to 60cm for Gymnotus carapo (Craig et al., 2019). The mouth of Gymnotus doesn’t open as wide as Apternotus and is generally a more shy fish, so would need much less competition. Gymnotus does provide a problem as while there is such a range in size the species provide issues for the fishkeeper in identifying, often small differences. G. carapo vs G. javari is at least easier, the former has the most vivid colouring with distinct black and white wide stripes maybe with spots but I think is slightly more arched in the back.

Sternarchorhynchus aff. mormyrus at night.

Feeding these two genera then if they can be fed on fry foods is the best for the range of vitamins, minerals and general nutrition. Otherwise Gymnotus can be a little more specialized requiring freeze dried, frozen or live foods but are at least generalists. For Gymnotus a range of frozen and freeze dried foods is a must but on top look around for different live foods appropriate for their mouth size, I feed my G. javari earthworms in terms of live foods to avoid those I cannot culture.

This is not typically a genus for the majority of tanks but they are illusive fishes regardless so take the real pet rock fish enthusiast. Gymnotus and two of the Apternotus would be the best choice for the majority of people.

Black ghost knifefish, Apternotus albifrons from Derek Ramsey (2005).

Habitat and setup

Gymnotiforme’s are illusive fishes, they will spend most of their time hiding whether it be in caves or some species will bury themselves in the sand (Escamilla-Pinilla et al., 2019). Therefore a wide diversity of different hiding spaces are a must for these fishes, while some might suggest glass caves given these fishes have eyes they can detect light and dark and would feel safer in a dark area.

There is quite the diversity in habitats but the majority of specialists are maybe more riparian/marginal species. Many of these smaller specialists species would enjoy a habitat with many botanicals or plants (Crampton, 2016) but this might not be possible due to trapping food although if lucky it could encourage smaller invertebrates like ostracods. While others exploit deep channels of water (Evans et al., 2019) therefore without these botanicals or leaf litter but large wood/and or rocks would be present. These found in areas of high botanicals it would be worth considering that they inhabit areas of very low pH and conductivity (Bichuette & Trajano, 2015). Of the larger more adaptable species inhabit a wider range of habitats, Gymnotus is shown to prefer a rocky habitat although can be found at surprisingly high pH (7.6-7.8) and conductivities of (170-190 uScm-1) according to Richer-de-Forges et al. (2009) .

Sociality

As with many fishes there are social Gymnotiformes and those less so. Many are social although as a curiosity Apternotus females are shown to be social whereas the males are ill-tolerant of other individuals (Henninger et al., 2020; Dunlap & Larkins‐Ford, 2003). Similarly Gymnotus javari are suggested to be social whereas the majority of the genus doesn’t tolerate other individuals (Westby & Box 1970; https://www.youtube.com/watch?v=OMRu_YUBE34). The more specialist species seem to be so much more social and even then many fishes seem to learn to feed from each other.

Identification

Outside of the two groups I recommend most the issue has to be identification and I have given clues how to identify a few. There is a lot more diversity and this makes this group tricky. It is certainly a taxa delving into the scientific literature outside of Apternotus where the black and brown ghost knives are obvious. So this does mean Gymnotus is a little risky with obtaining a species that can grow much larger.

Conclusion

To write a whole article about Gymnotiformes without mentioning their amazing electrical abilities, well that doesn’t entirely concern us as fishkeepers with the exception of Electrophorus, the electric eel of which needs an article of it’s own. These are also likely very intelligent fishes who would benefit from a tank that has a variety of decor and landscapes.

References:

Albert, J. S., & Crampton, W. G. (2005). Diversity and phylogeny of Neotropical electric fishes (Gymnotiformes). In Electroreception (pp. 360-409). New York, NY: Springer New York.

Bichuette, M. E., & Trajano, E. (2015). Population density and habitat of an endangered cave fish Eigenmannia vicentespelaea Triques, 1996 (Ostariophysi: Gymnotiformes) from a karst area in central Brazil. Neotropical Ichthyology, 13, 113-122.

Craig, J. M., Kim, L. Y., Tagliacollo, V. A., & Albert, J. S. (2019). Phylogenetic revision of Gymnotidae (Teleostei: Gymnotiformes), with descriptions of six subgenera. PLoS One, 14(11), e0224599.

Crampton, W. G., De Santana, C. D., Waddell, J. C., & Lovejoy, N. R. (2016). Phylogenetic systematics, biogeography, and ecology of the electric fish genus Brachyhypopomus (Ostariophysi: Gymnotiformes). PLoS One, 11(10), e0161680.

de Santana, C. D., & Crampton, W. G. (2011). Phylogenetic interrelationships, taxonomy, and reductive evolution in the Neotropical electric fish genus Hypopygus (Teleostei, Ostariophysi, Gymnotiformes). Zoological Journal of the Linnean Society, 163(4), 1096-1156.

de Santana, C. D., Crampton, W. G., Dillman, C. B., Frederico, R. G., Sabaj, M. H., Covain, R., … & Wosiacki, W. B. (2019). Unexpected species diversity in electric eels with a description of the strongest living bioelectricity generator. Nature communications, 10(1), 1-10.

Dunlap, K. D., & Larkins‐Ford, J. (2003). Production of aggressive electrocommunication signals to progressively realistic social stimuli in male Apteronotus leptorhynchus. Ethology, 109(3), 243-258.

Escamilla-Pinilla, C., Mojica, J. I., & Molina, J. (2019). Spatial and temporal distribution of Gymnorhamphichthys rondoni (Gymnotiformes: Rhamphichthyidae) in a long-term study of an Amazonian terra firme stream, Leticia-Colombia. Neotropical Ichthyology, 17, e190006.

Evans, K. M., Kim, L. Y., Schubert, B. A., & Albert, J. S. (2019). Ecomorphology of neotropical electric fishes: an integrative approach to testing the relationships between form, function, and trophic ecology. Integrative Organismal Biology, 1(1), obz015.

Ford, K. L., Bernt, M. J., Summers, A. P., & Albert, J. S. (2022). Mosaic evolution of craniofacial morphologies in ghost electric fishes (Gymnotiformes: Apteronotidae). Ichthyology & Herpetology, 110(2), 315-326.

Fricke, R., Eschmeyer, W. N. & Van der Laan, R. 2024. ESCHMEYER’S CATALOG OF FISHES: GENERA, SPECIES, REFERENCES. (http://researcharchive.calacademy.org/research/ichthyology/catalog/fishcatmain.asp).

Giora, J., Tarasconi, H. M., & Fialho, C. B. (2014). Reproduction and feeding of the electric fish Brachyhypopomus gauderio (Gymnotiformes: Hypopomidae) and the discussion of a life history pattern for gymnotiforms from high latitudes. PloS one, 9(9), e106515.

Golubtsov, A. S., & Darkov, A. A. (2008). A review of fish diversity in the main drainage systems of Ethiopia based on the data obtained by 2008. In Ecological and faunistic studies in Ethiopia, Proceedings of jubilee meeting “Joint Ethio-Russian Biological Expedition (Vol. 20, pp. 69-102). Moscow: KMK Scientific Press.

Gonçalves-Silva, M., Luduvice, J. S., Gomes, M. V. T., Rosa, D. C., & Brito, M. F. (2022). Influence of ontogenetic stages and seasonality on the diet of the longtail knifefish Sternopygus macrurus (Gymnotiformes, Sternopygidae) in a large Neotropical river. Studies on Neotropical Fauna and Environment, 57(1), 11-17.

Henninger, J., Krahe, R., Sinz, F., & Benda, J. (2020). Tracking activity patterns of a multispecies community of gymnotiform weakly electric fish in their neotropical habitat without tagging. Journal of Experimental Biology, 223(3), jeb206342.

Lundberg, J. G., & Mago-Leccia, F. (1986). A review of Rhabdolichops (Gymnotiformes, Sternopygidae), a genus of South American freshwater fishes, with descriptions of four new species. Proceedings of the Academy of Natural Sciences of Philadelphia, 53-85.

Mucha, S., Chapman, L. J., & Krahe, R. (2021). The weakly electric fish, Apteronotus albifrons, actively avoids experimentally induced hypoxia. Journal of Comparative Physiology A, 207(3), 369-379.

Richer-de-Forges, M. M., Crampton, W. G., & Albert, J. S. (2009). A new species of Gymnotus (Gymnotiformes, Gymnotidae) from Uruguay: description of a model species in neurophysiological research. Copeia, 2009(3), 538-544.

Tagliacollo, V. A., Bernt, M. J., Craig, J. M., Oliveira, C., & Albert, J. S. (2016). Model-based total evidence phylogeny of Neotropical electric knifefishes (Teleostei, Gymnotiformes). Molecular phylogenetics and evolution, 95, 20-33.

Westby, G. M., & Box, H. O. (1970). Prediction of dominance in social groups of the electric fish, Gymnotus carapo. Psychonomic Science, 21(3), 181-183.

Lighting a Fish Tank

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The majority of discussions regarding lighting in the aquarium is very plant centric, plants depend on light to a much higher degree then animals. Although the extent that aquarists looking at plant growth goes to maybe verges on the unnatural, probably because many aquarium plants we keep are not naturally aquatic so some are evolved for much higher degrees of lighting.

Fishes having eyes and melanin so do respond to and can see light (Guthrie, 1986). Previously in an article focusing on UVB and lighting intensity I discuss the importance for enhancing colouration particularly and any benefits of UVB. In this article I want to talk more in a broader sense of the importance for lighting itself rather then to go into depth on aspects of the lighting spectrum.

One of the largest debates in animal biology regarding vision is how much can they see, fishes is a large category and even in freshwater there will be a massive diversity in colour vision. Some fishes also do not have any eyes, usually due to a trilobite lifestyle in caves, only the Mexican cave fish, Astyanax mexicanus seems to really enter the aquarium trade with any frequency and some of these have reduced eyes known as microphthalmia (Borowsky, 2018). Unlike many other vertebrates fishes display other senses (Gill, 2018) that allow many to cope without eyes as some fishkeepers might have noticed after their fish had lost one or both.

What colour should my lights be?

Generally it would be considered the most natural light would be white light and this is partially true, it has the widest range of colours in it after all. One thing to consider if we are replicating a fishes habitat and wanting to give them lighting that will benefit them is the influence of depth. The deeper the water the more certain colours are filtered out such as reds. I personally think that unless you are using the brightest colouration for an aim it probably has no benefit to the fishes, personally I much prefer those warmer tones. We do know at least in humans the actual colours of the spectrum exposed to the eye does effect the physiology so I personally think this means that white light is so important.

Many freshwater fishes are tetrachromatic, having four colour cone receptors in the eye rather then the three of typical humans or two-three of reef fishes (Marshall et al., 2019). This colour vision does depend on the light intensity, so at lower intensities freshwater fishes tend to be trichromatic (Neumeyer & Arnold, 1989). So this does pose an issue where people use blue lights to watch particularly catfishes at night, if the fishes can see that blue light it is likely disrupting them. I personally would only recommend doing this for short periods so the fish can rest. It might also be a factor that if using only blue lights the lighting is dimmer anyway which is why they are more active rather then them thinking it’s night. Personally I’d rather use a camera for hidden behaviour.

How long should lights be on? If at all?

Fishes much like humans have an internal clock known as a Circadian rhythm, this can be influenced by multiple factors but in particular light (Vera et al., 2023). This means having a regular cycle where the lights are on and off is beneficial. This is not just limited by eyes, even without eyes certain physiology can occur meaning a fish can identify day and night (Frøland Steindal & Whitmore, 2019). This means a regular schedule of day and night is important for fishes much like with people, changes seasonally would work.

There is no doubt a range in nocturnal and and diurnal fishes that we keep, probably many are also crepuscular. The length of time required to sleep likely also varies between individuals and species, some taking short frequent rest periods and much longer periods (Reebs et al., 1992). Sleep is incredibly important for fishes, so it is a necessity to provide that time for them (Leung et al., 2019).

References:

Borowsky, R. (2018). Cavefishes. Current Biology, 28(2), R60-R64.

Frøland Steindal, I. A., & Whitmore, D. (2019). Circadian clocks in fish—what have we learned so far?. Biology, 8(1), 17.

Gill, A. B. (2019). The sensory ecology of fishes. Journal of Fish Biology, 95(1), 3-4.

Guthrie, D. M. (1986). Role of vision in fish behaviour. In The behaviour of Teleost fishes (pp. 75-113). Boston, MA: Springer US.

Leung, L. C., Wang, G. X., Madelaine, R., Skariah, G., Kawakami, K., Deisseroth, K., … & Mourrain, P. (2019). Neural signatures of sleep in zebrafish. Nature, 571(7764), 198-204.

Marshall, N. J., Cortesi, F., de Busserolles, F., Siebeck, U. E., & Cheney, K. L. (2019). Colours and colour vision in reef fishes: Past, present and future research directions. Journal of Fish Biology, 95(1), 5-38.

Neumeyer, C., & Arnold, K. (1989). Tetrachromatic color vision in the goldfish becomes trichromatic under white adaptation light of moderate intensity. Vision research, 29(12), 1719-1727.

Reebs, S. (1992). Sleep, inactivity and circadian rhythms in fish. In Rhythms in fishes (pp. 127-135). Boston, MA: Springer US.

Vera, L. M., de Alba, G., Santos, S., Szewczyk, T. M., Mackenzie, S. A., Sánchez-Vázquez, F. J., & Planellas, S. R. (2023). Circadian rhythm of preferred temperature in fish: Behavioural thermoregulation linked to daily photocycles in zebrafish and Nile tilapia. Journal of Thermal Biology, 113, 103544.

Pathogens in Aquarium Fishes: 2. Spots, Bumps and Lumps

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Many fishes display lumps, spots and bumps which can happen due to a range of pathological conditions whether it being pathogens or other factors. These can easily be confused and if concerned or confused please consult a fish pathologist or trained fish specialist veterinarian. This page is only to help give some clarity

All sources here are from scientific papers and many of the images from these papers for a reliable diagnosis unless otherwise stated for clarity purposes.

Microscopy is required in many cases for a confirmed diagnosis and therefore I recommend their use. Some stores might have one available to be used. In other cases more advanced diagnostic techniques might be required and provided by a pathologist via a veterinarian.

Diseases featured:

White spot/ich (Ichthyophthirius multifiliis)

Protozoan ciliate pathogen which can cause large mortalities in later stages.

*Ichthyophthirius multifiliis* on a Rift Valley cichlid, *Aulonocara* sp.? Image obtained from: Thomas Kaczmarczyk (www.djpalme.de.vu) on Wikipedia.

Occurrence: Seems to be very common and in my opinion largely occurs when fish are sufficiently stressed.

Diagnostics: White spots on the body of the fish, can also be accompanied by shedding of the slime coat. The spots can be varied in size and number. This ciliate additionally targets the gills where it causes the most stress on the fish (Yang et al., 2023; Mallik et al., 2013). This spotted appearance is commonly confused with Epistylis which if symptomatic (of which mostly it is not) appears more as a plaque so will not appear in this article (ESHA video; Ksepka et al., 2021; Valladao et al., 2015; Wang et al., 2017, Wu et al., 2021). Both pathogens can appear with Aeoromonas bacteria that additionally causes hemorrhaging (Kumar et al., 2022).

Microscopic image:

Ichthyophthirius multifiliis under the microscope, images obtained from Yang et al (2023). Yang, H., Tu, X., Xiao, J., Hu, J., & Gu, Z. (2023). Investigations on white spot disease reveal high genetic diversity of the fish parasite, Ichthyophthirius multifiliis (Fouquet, 1876) in China. *Aquaculture*, *562*, 738804.

Treatment: The most frequent treatments provided in the aquarium hobby is malachite green with either formalin, formaldehyde or copper. Obviously copper is often a concern for those with invertebrates in the aquarium. Salt the old age treatment can work and as a study ABDULLAH-AL MAMUN et al. (2021) infers it depends on time of treatment. There seems to be a multitude of papers narrowing down the best treatment and to me this infers maybe there is no real answer, there might be increasing immunity of the ciliate or just this species is so diverse. Generally it’s assumed the best method is to avoid introducing any fish showing symptoms or on the same system with those who do. Copper sulphate additionally has been shown to treat white spot (Schlenk et al., 1998). In a later 2008 study formalin did not have any effect on the ciliate whereas copper treated it within 14 days (Rowland et al., 2008) which is around two rounds of treatment by most bottles. I therefore just looking at these three studies would not recommend formalin and maybe therefor formaldehyde for treatment and instead focus on copper and maybe salt needs further examination.

One of the most unusual parasites of fishes being an algae known as dinoflagellates.

*Piscinoodinium pillulare* outbreaks: piscinootest. *Ciência Rural*, 48. on the gills of a fish (Gomes et al., 2018). Gomes, A. L. S., Costa, J. I. D., Benetton, M. L. F. D. N., Bernardino, G., & Belem-Costa, A. (2018). A fast and practical method for initial diagnosis of *Piscinoodinium pillulare* outbreaks: piscinootest. *Ciência Rural*, 48.

Piscinoodinium spp. infections (Esmail et al., 2015). Image obtained from: Esmail, M. Y., Astrofsky, K. M., Lawrence, C., & Serluca, F. C. (2015). The biology and management of the zebrafish. In *Laboratory animal medicine* (pp. 1015-1062). Academic Press.

Occurrence: Reasonably common, I can’t comment on cause. It seems Oodinium seems to be less common then Piscinoodinium.

Diagnostics: Different from white spot, being algaes they tend to have some coloration to them. Usually appears as small golden spots across the body, the fish are often lethargic. Mortality is not particularly rapid (Levy et al., 2007). It is not always obvious beyond hemorrhaging (Sudhagar et al., 2022).

Microscopic image: Not entirely required and diverse, although can make it easier to compare.

*Piscinoodinium* sp. copied from Sudhagar et al. (2022). Sudhagar, A., Sundar Raj, N., Mohandas, S. P., Serin, S., Sibi, K. K., Sanil, N. K., & Raja Swaminathan, T. (2022). Outbreak of Parasitic Dinoflagellate Piscinoodinium sp. Infection in an Endangered Fish from India: Arulius Barb (Dawkinsia arulius). *Pathogens*, 11(11), 1350.

Treatment: Treatment rarely seems discussed. As these are photosynthetic I agree with many aquarists that keeping the lights off for even two weeks will not harm the fish and even if it minorly effects the algae that’s better then nothing. The aquarium hobby largely jumps to copper based treatments along with malachite green mixed in with methylene blue, it doesn’t seem the most resistant pathogen and I wonder additionally if a fishes immune system handles some of it. Copper is suggested to work (Lieke et al., 2020). There seems to be no research on methylene blue other then being an anti-protozoan compound. Similarly with malachite green, no treatments even salt have any strong background to their effectiveness. The other issue is these compounds can effect the microbes within the aquarium (Yang et al., 2021). All I can say is I had success with the NT labs anti-parasite treatment containing copper sulphate and formaldehyde along with switching the lights off.

Dermocystidium

The strangest in appearance of pathogens, much like a worm but far from that, their taxonomic placement is unclear but they don’t move.

Occurrence: Reasonably frequent with a diversity of fishes soon after obtaining.

Diagnostics: Worm like in a variety of forms and size, can be encapsulated by pectoral fins or around the body. Some might appear singularly other fishes might have a lot more. These do not move like nematodes but are extremely diverse (Fujimoto, et al., 2018; Persson et al., 2022).

Microscope image: Not required.

Treatment: It is largely agreed in the aquarium trade which I agree that these protozoans as unsightly as they are do disappear with time and handled by the fishes own immune system.

Worm cysts

Not really possible to obtain much scientific research on the topic with the time I have free. But it does happen and seems frequent with wild imports.

Occurrence: Not common at all, seems to arrive with import.

Diagnostics: Looks much like white spot but larger cysts. Stubborn and white spot treatments do not work regardless of the fish showing no lethargy or poor health.

Microscope image: Usually distinctively different from white spot velvet by size and shape.

Treatment: As suggested by the name, wormers tend to work. I cannot remember which I used but likely first praziquantel, levamisole and flubendazole might work as well.

Tumors

If a tumor occurs certainly this is a situation where veterinarians are recommended.

Occurrences: There are many caused within fishes, sometimes it is genetic causes such as in the dragon scale of Betta splendens, viral causes (Coffee et al., 2013) or dietary (Žák et al., 2022). On a quick scan of the literature papilloma viruses are not associated with tumors.

Diagnosis: These can be large growths, they can be vascularized supplied by blood vessels. Unlike viral growths on my observations tend to be rounder and do not appear in many numbers.

Microscopy: Not required.

Treatment: Discuss with a specialist fish veterinarian.

Viral papilloma and herpes viruses

These are commonly mistaken for lymphocystis and can be very complex growths. Technically Papilloma refers to epithelial groups but can display similarly to herpes viruses. In the aquarium trade it doesn’t seem clear which we are handling and regardless treatment is the same. A wide range of herpes viruses are associated with fishes from KHV, carp pox (Davison et al., 2013) and channel catfish herpesvirus (Davison et al., 1992).

Viral papilloma’s likely caused by a Papillomavirus (PV) in a *Pterygoplichthys pardalis,* image sourced from Reddit, poster: Render et al., 1721.

Occurrence: Seems reasonably common right now. This virus I can assume once contracted is not removed from the fishes body but are suppressed by the immune system. Koi Herpes Virus (KHV) is fatal and while not wildly common any suspected occurrence might require contacting environmental authorities.

Diagnosis: These are round or very tuberous numerous growths, much more like warts while symptomatic but asymptomatic individuals and time might not display any symptoms (Tarján et al., 2022; Rahmati-Holasoo et al., 2015). Very understudied when it comes to aquarium fishes so whether we are dealing with a herpes or traditional papilloma virus is difficult to say. Rahmati-Holasoo et al. (2015) infers that most viral growths we are seeing in Loricariids is caused by a Papillomavirus, although a previous study by Hedrick et al., (1996) in carp inferred similar growths and concluded due to a herpes virus.

Treatment: Time, these viruses cannot be cured only prevention of introduction. Very few are fatal. These viruses are generally specific to closely related fishes so transfer should not be an issue.

Sources for koi and carp pox:

https://cafishvet.com/fish-health-disease/koi-pox-aka-carp-pox

https://canalrivertrust.org.uk/things-to-do/fishing/caring-for-our-fish/guide-to-fish-health/koi-herpesvirus-khv

https://marinescience.blog.gov.uk/2015/10/02/koi-herpesvirus-khv-disease-and-fisheries

Unknown growths

There is a wide range of unknown growths in fishes we can only make assumptions, veterinary professionals and vets would be worth consulting. I have seen a number which didn’t conform with any of these.

References:

ABDULLAH-AL MAMUN, M. D., NASREN, S., RATHORE, S. S., & RAHMAN, M. M. (2021). Mass infection of Ichthyophthirius multifiliis in two ornamental fish and their control measures. Annals of Biology, (2), 209-214.

Coffee, L. L., Casey, J. W., & Bowser, P. R. (2013). Pathology of tumors in fish associated with retroviruses: a review. Veterinary Pathology, 50(3), 390-403.

Davison, A. J. (1992). Channel catfish virus: a new type of herpesvirus. Virology, 186(1), 9-14.

Davison, A. J., Kurobe, T., Gatherer, D., Cunningham, C., Korf, I., Fukuda, H., … & Waltzek, T. B. (2013). Comparative genomics of carp herpesviruses. Journal of Virology, 87(5), 2908-2922.

Esmail, M. Y., Astrofsky, K. M., Lawrence, C., & Serluca, F. C. (2015). The biology and management of the zebrafish. In Laboratory animal medicine (pp. 1015-1062). Academic Press.

Fujimoto, R. Y., Couto, M. V. S., Sousa, N. C., Diniz, D. G., Diniz, J. A. P., Madi, R. R., … & Eiras, J. C. (2018). Dermocystidium sp. infection in farmed hybrid fish Colossoma macropomum× Piaractus brachypomus in Brazil. Journal of Fish Diseases, 41(3), 565-568.

Gomes, A. L. S., Costa, J. I. D., Benetton, M. L. F. D. N., Bernardino, G., & Belem-Costa, A. (2018). A fast and practical method for initial diagnosis of Piscinoodinium pillulare outbreaks: piscinootest. Ciência Rural, 48.

Hedrick, R. P., Groff, J. M., Okihiro, M. S., & McDowell, T. S. (1990). Herpesviruses detected in papillomatous skin growths of koi carp (Cyprinus carpio). Journal of Wildlife Diseases, 26(4), 578-581.

Ksepka, S. P., & Bullard, S. A. (2021). Morphology, phylogenetics and pathology of “red sore disease”(coinfection by Epistylis cf. wuhanensis and Aeromonas hydrophila) on sportfishes from reservoirs in the South‐Eastern United States. Journal of Fish Diseases, 44(5), 541-551.

Kumar, V., Das, B. K., Swain, H. S., Chowdhury, H., Roy, S., Bera, A. K., … & Behera, B. K. (2022). Outbreak of Ichthyophthirius multifiliis associated with Aeromonas hydrophila in Pangasianodon hypophthalmus: The role of turmeric oil in enhancing immunity and inducing resistance against co-infection. Frontiers in immunology, 13, 956478.

Levy, M. G., Litaker, R. W., Goldstein, R. J., Dykstra, M. J., Vandersea, M. W., & Noga, E. J. (2007). Piscinoodinium, a fish-ectoparasitic dinoflagellate, is a member of the class Dinophyceae, subclass Gymnodiniphycidae: convergent evolution with Amyloodinium. Journal of Parasitology, 93(5), 1006-1015.

Lieke, T., Meinelt, T., Hoseinifar, S. H., Pan, B., Straus, D. L., & Steinberg, C. E. (2020). Sustainable aquaculture requires environmental‐friendly treatment strategies for fish diseases. Reviews in Aquaculture, 12(2), 943-965.

Mallik, S. K., Shahi, N., Das, P., Pandey, N. N., Haldar, R. S., Kumar, B. S., & Chandra, S. (2015). Occurrence of Ichthyophthirius multifiliis (White spot) infection in snow trout, Schizothorax richardsonii (Gray) and its treatment trial in control condition. Indian Journal of Animal Research, 49(2), 227-230.

Persson, B. D., Aspán, A., Bass, D., & Axén, C. (2022). A case study of Dermotheca gasterostei (= Dermocystidium gasterostei, Elkan) isolated from three-spined stickleback (Gasterosteus aculeatus) captured in lake Vättern, Sweden. Bulletin of the European Association of Fish Pathologists.

Rahmati-Holasoo, H., Shokrpoor, S., Mousavi, H. E., & Ardeshiri, M. (2015). Concurrence of inverted-papilloma and papilloma in a gold spot pleco (Pterygoplichthys joselimaianus Weber, 1991). Journal of Applied Ichthyology, 31(3), 533-535.

Rowland, S. J., Mifsud, C., Nixon, M., Read, P., & Landos, M. (2008). Use of formalin and copper to control ichthyophthiriosis in the Australian freshwater fish silver perch (Bidyanus bidyanus Mitchell). Aquaculture research, 40(1), 44-54.

Schlenk, D., Gollon, J. L., & Griffin, B. R. (1998). Efficacy of copper sulfate for the treatment of ichthyophthiriasis in channel catfish. Journal of Aquatic Animal Health, 10(4), 390-396.

Sudhagar, A., Sundar Raj, N., Mohandas, S. P., Serin, S., Sibi, K. K., Sanil, N. K., & Raja Swaminathan, T. (2022). Outbreak of Parasitic Dinoflagellate Piscinoodinium sp. Infection in an Endangered Fish from India: Arulius Barb (Dawkinsia arulius). Pathogens, 11(11), 1350.

Tarján, Z. L., Doszpoly, A., Eszterbauer, E., & Benkő, M. (2022). Partial genetic characterisation of a novel alloherpesvirus detected by PCR in a farmed wels catfish (Silurus glanis). Acta Veterinaria Hungarica, 70(4), 321-327.

Valladao, G. M. R., Levy-Pereira, N., Viadanna, P. H. D. O., Gallani, S. U., Farias, T. H. V., & Pilarski, F. (2015). Haematology and histopathology of Nile tilapia parasitised by Epistylis sp., an emerging pathogen in South America. Bulletin of the European Association of Fish Pathologists, 35(1), 14-20.

Yang, C. W., Chang, Y. T., Hsieh, C. Y., & Chang, B. V. (2021). Effects of malachite green on the microbiomes of milkfish culture ponds. Water, 13(4), 411.

Yang, H., Tu, X., Xiao, J., Hu, J., & Gu, Z. (2023). Investigations on white spot disease reveal high genetic diversity of the fish parasite, Ichthyophthirius multifiliis (Fouquet, 1876) in China. Aquaculture, 562, 738804.

Wang, Z., Zhou, T., Guo, Q., & Gu, Z. (2017). Description of a new freshwater ciliate Epistylis wuhanensis n. sp.(Ciliophora, Peritrichia) from China, with a focus on phylogenetic relationships within family Epistylididae. Journal of Eukaryotic Microbiology, 64(3), 394-406.

Wu, T., Li, Y., Zhang, T., Hou, J., Mu, C., Warren, A., & Lu, B. (2021). Morphology and molecular phylogeny of three Epistylis species found in freshwater habitats in China, including the description of E. foissneri n. sp.(Ciliophora, Peritrichia). European Journal of Protistology, 78, 125767.

Aquarium Fish Diseases For Fishkeepers – The Basics

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Like any other organism fishes can host pathogens and contract diseases, unlike many other pet related hobbies we are dealing with a wide diversity of different species. The diseases of aquarium fishes is there for a vast topic.

As my specialty is in the evolutionary biology of fishes, diseases are not my specialty. That is not to say like any other fish biologist I do not encounter them, given I am often not using high magnifications I actually am more familiar with larger ectoparasites then bacteria or protozoa. I do have a background in taxonomy as well so am familiar with understanding how even these bacteria, protozoa, fungi etc. are diagnosed to a degree.

Previously there have been many brilliant aquarium books focused on disease and I think more then anything I recommend an aquarist to have at least one. These books were often written by those with a background in pathology, included images of microscope slides and based in science.

Books I’d recommend (there will be others I have forgotten):

Discus Health, TFH Publication by Dieter Untergasser
Handbook of Fish Diseases, TFH Publication by Dieter Untergasser.
The Interpet Manual of Fish Health: Everything You Need to Know About Aquarium Fish, Their Environment and Disease Prevention, Firefly Books Ltd by Dr. Chris Andrews, Adrian Excell and Dr Neville Carrington.
The Practical Guide to Fish Diseases by Dr. Gerald Bassleer

The main issue with disease is to take anything also marketing a product with a pinch of salt unless it’s discussing a general compound e.g. malachite green, formaldehyde etc.

Diseases of aquarium fishes has become one of the most hotly contested topics within the aquarium hobby of recent years. With many websites making unfounded claims that lack citations where maybe they should to backup any novel ideas or information. This makes diagnosing disease for the general fishkeeper rather challenging. I hope I can make it a little easier or give areas to start researching.

This topic will cover multiple articles and therefore this contents should help guide a user through this page and others.

*Corydoras* (*syn. Brochis*) at Wildwoods, Enfield.

Preventative care to avoid disease

One of the biggest factors when it comes to any organism of preventing disease is ensuring the organism is healthy. There are several influences that might mean a fish is stressed enough to become more susceptible to disease; behavioral, environmental and also diet. If an organism is stressed then the immune system might not be functioning as well as it could and will be less able to fend of disease, this isn’t something new. Some disease might additionally be directly caused by these factors rather then by external pathogens.

So, lets explore preventative care.

Preventing disease by understanding specific fish behavior.

This is probably the most difficult to identify and sometimes the most difficult to cater for as we know so little about fish behavior. Here there are probably two outcomes of not catering for a fishes behavior; poor physiological health or abnormal behavior.

Poor physiological health is very obvious, a fish might have tattered fins, lost scales and reduced colouration. It could be that the fish is being directly attacked in territorial aggression or from a more predatory tankmate. In some fishes just simply removing an offending individual might solve the issue but with some fishes such as the Aulonocara (peacock cichlids), mbuna (multiple genera), Haplochromis etc. of the Rift valley this can create instability in the social hierarchy of the group (Piefke et al., 2021). Of course removing some worst offending species would maybe be a benefit and therefore considering what species are to be included to start off. These voids in hierarchy can create more aggression as individuals are additionally are then identifying where they all fit. It’s a common assumption to assume aggression is male focused, as I discuss in a previous article females do frequently display aggression (Female Aggression).

Aggression can just be simply territorial, Neolamprologous cichlids can be good examples of this where individuals will maintain a space and the location based often on maintaining resources reproductive, predator protection and dietary. Fish sociality can be so very complex so it’s not entirely simple (Walter et al., 1994). This territoriality can also be seen in many Loricariids (Plecos) but also Anabantoids such as Channa or gourami’s, not always related to reproduction but just defense of a space.

Even many shoaling species might show aggression and therefore in that context a good number with an appropriate sex ratio would be best. Sociality in many species is important though, even if it is fleeting there is a behavioral enrichment, this isn’t always possible. But for shoaling and schooling species having others of the same species or population is important.

Many popular fishes can be counted as some what shoaling or schooling such as clown loaches, Chromobotia macracanthus to neon tetra, Paracheirodon innesi. These fishes alone or even in small numbers such as 3 or 6 depending on the species you might see abnormal behavior. Sometimes difficult to identify as some species are just illusive. A shoaling species kept alone could be illusive, swim erratically around the glass or even maybe shoaling with a different species. It’s definitely very context dependent. Sociality is important for behavioral and maybe even physiological development (Riley et al., 2018), we know that though from other verebtrates……. The understanding of species can be difficult but realistically multiple individuals of different species would not make up a shoal. Whether it be Corydoras or tetra, these species might not be closely related but even if they are it doesn’t mean they can communicate and therefore benefit socially. In other fishes such as discus communication is so much in their coloration given they can recognize individuals (Satoh et al., 2016), many varieties have lost or altered this ability and could result in communication issues between domestics, wilds and certain varieties. This means it’s highly likely discus can identify the different species and even populations. I have experienced this myself. Just by the fact so many fishes of the same genus or group are located together behavior likely results in this speciation.

Tankmates themselves can provide another kind of harm, they could be eaten and vice versa. Generally avoiding tankmates that will fit in the mouth is a good rule of measure. Some fishes can expand their mouth further then expected and while many are gape limited (limited by the size of their mouth) others this limitation is minor. Even the slowest fish are more then capable of eating faster fishes, discus feeding on cardinal/neon tetra is commonly accounted and goldfish frequently feed on smaller tankmates. The biggest risk here is if the smaller fish is too big to be swallowed down and that larger fish chokes.

Goldfish, *Carassius aureatus* choking on an *Otocinclus* sp. the catfish had been housed with the goldfish for 2 years before this situation. Photo used with permission from the owner and the Facebook group: Goldfish Care.

The effect of the environment on fish disease.

More then often we think of the environment as purely about water parameters in fishes but the actual décor is important as well. I have been a long standing admin of goldfish groups and frequently seen where they have choked on gravel for example.

This is so diverse as so much can effect a fishes health.

Water parameters

The influence of water parameters on the health of fishes is so complex and so diverse, here I wont discuss hardness I have discussed it partially in the article on pH and hardness (here). Associated with mismanagement of hardness is gas bubble disease of which would require it’s own article or discussion, it is likely confused with a pH crash due to how quickly it occurs.

So, the main parameters we will focus on will be those related to nitrogen; ammonia, nitrites and nitrates. The values which cause death will vary depending on the fish and other parameters, many effects might seem asymptomatic unless a dissection is undertaken so do not assume because you cannot see an effect the fish isn’t affected. Ammonia itself burns the gills (Liu et al., 2021) but largely targets the the brain (Ip & Chew et al., 2010). Nitrite is the most well known as crossing into the blood combining with the blood to form methaemoglobin resulting in less oxygen carried around the body (Ciji & Akhtar, 2020), it can kill particularly rapidly seeming like a crash. These all are managed by a stable and cycled aquarium. Nitrate is maybe the least understood and the least studied as most studies focus on fishes with particular adaptability. This compound functions the same way as nitrites by combining with the blood to reduce oxygen saturation within the blood at higher volumes (Camargo et al., 2005). Many websites and a number of Youtubers focus on whether it kills but it shouldn’t be about rapid deaths rather long term effects, this is likely due to promoting methods where high nitrates are inevitable (Hrubec et al., 1996). So the question about low volumes becomes difficult, this is because most studies are short term and on fishes completely different from what we keep but even Hrubec et al. (1996) displays the toxicity of nitrate. It is better to assume toxicity then not just for the sake of water changes and half an hour or few hours a week, after all no one would argue for mammals to be left in their own waste because of intensive farming methods that do so.

Most of these nitrogen based compounds effect how oxygen is taken up whether it’s from burning the gills or the binding to the blood. So increasing oxygenation will not be harmful, methylene blue in small volumes is associated with increasing oxygen saturation in humans although it is difficult to find any research into the topic. Olufayo and Yusuf (2016) suggested that volumes of 67ppm to 199ppm of methylene blue didn’t increase oxygen saturation but previous research lists methylene blue as decreasing the solubility of oxygen (Khan et al., 2022). One aspect could be that largely when used in medicine it’s in humans and direct in the body, for fishes it’s added into the water so I think there is a whole other level of things at play. Another aspect of treating any higher values of these compounds is the use of Seachem prime, yes it does but decrease oxygen saturation so there is a balance (Seachem’s website).

Substrate

One of the things that least comes to mind when it comes to the health of fishes is substrates, there is so much diversity of them in stores and this can be overwhelming. Some might interact with the water parameters which is not usually ideal for many fishes as the focus of these is on plants.

The biggest risk substrate is gravels with any fish that might dig around in the substrate. It is frequently accounted particularly with goldfish where the gravel becomes stuck in either the oral or pharyngeal jaws of the fish.

Some of many situations where goldfish have choked on goldfish, used with permission of the owners and the facebook group: Goldfish Care.

Just as seriously from gravel is impaction although I have never encountered a certain case myself, if that gravel enters the digestive tract it wont exit easily unlike sand of which many fishes pass through their gut even in larger amounts harmlessly (Lujan et al., 2012).

Substrates offer an enrichment for so many fishes which is very important to recognise as so many species naturally search for food. I would rarely have a tank without it. The safest and most natural for many species is sands. One of these fishes that benefits so much are Corydoras and a number of loaches. Sharp substrates in these fishes is associated with erosion of the barbels present around the mouth although there is no studies on the topic and it is sometimes associated with the bacteria that gravel traps. This erosion leaves open wounds and an area highly open to infection.

*Corydoras sterbai* with erosion of the barbels caused by the sharp gravel and substrate. Image sourced from Aquarium Coop Forum, CARE and the user BMBSAD.

décor

This is probably the most logical but in the stress of setting up a tank it can be a bit overwhelming to decide what to get. Generally consider if you are having any secretive fishes they will need plenty of spaces to hide in a variety of shapes and sizes, being exposed can be stressful for them and you’ll see the stress patterning on them. When it comes to these fishes always be sure there isn’t decor that the fish can get stuck on, this seems more of an issue with artificial décor then natural.

Sharp décor can also cause wounds whether it be the metal rods in silk plants or sharp dragon rock, for many fishes this is no issue but for clumsy species or some bottom dwellers accidents happen. Some species which might have very rough spawning or aggressive behaviour then they can bash against décor so maybe avoiding anything too rough here but we shouldn’t exchange enrichment to almost bubble wrap our fishes.

Some items might have a risk if eaten, I am not sure how true this is but some people do record rasping fishes such as Loricariids feeding on the paint of some artificial décor. This is probably best avoided just because of the potential chemicals. Similar any decor from plastics you are not familiar with and might degrade in the water releasing microplastics or other compounds.

Conclusion

Obviously for preventative care there is so much more that needs to be considered. Think about the habitats these fishes experience in the wild. Observe your fishes and their behaviour, sometimes it’s worth doing so from a distance so they aren’t expecting food either that or a camera to see them at night. Some behaviour is not always seen.

What are pathogens?

Pathogens are organisms that cause disease. These in fishes can be as followed:

Viruses: Debatable if they are alive and therefore an organism. These cannot therefore do not have any treatment against them beyond keeping the immune system at it’s best and preventative care. Some viruses cannot be ‘cured’ and will always exist within the fish and some the fishes immune system will kill. Some viruses are fatal to the fish and others are not.
Bacteria: This is a massive group of organisms. Unlike viruses and like all the other groups I will later list not all are pathogens or parasites, many have different roles. These can be killed by a variety of treatments and by the fishes immune system.
Protozoa: This is a paraphyletic group of random organisms, not all are parasitic and some can be particularly difficult to treat while others much easier. A huge diversity of organisms.
Annelid/worms: Very few are ever seen in the aquarium other then leeches, these are true worms and more tricky to treat.
Nematodes: Similar to worms but not closely related at all. These are most often known for inhabiting the digestive tract or tissues in cysts. Many different wormers target this group.
Copepods, isopods: Easier to see in most situations and best removed by hand if spotted, these larger Arthropod invertebrates can be difficult to treat once becoming an infestation. The only ones a fishkeeper will usually encounter is fish lice, Argulus sp.
Algaes: The least obvious group to be parasitic/pathogenic but many are, velvet (Oodinium spp.) and related species with similar symptoms are reasonably common. This includes Cyanobacteria which are still algaes (Yanong et al., 2002). Technically as quite a lot of algae’s are protozoan and similar treatments sometimes work.

Disease and pathogen specificity.

Diseases and pathogens can be specific to certain groups of fishes or sometimes certain age demographics. A great example is some herpes type viruses many of which are specific to certain species or families (Hanson et al., 2011). This does mean if one fish has such a virus it wont be contracted by other taxa. You will also not find any confirmed cases of some diseases/pathogens in some fishes e.g. lymphocystis in carp and catfishes.

This is likely due to a diversity of different physiology between species, genera and even further families and more. Biology in general can differ so much certain groups might prevent access to certain taxa or they might lack the target organs and tissues.

Some individuals might be asymptomatic to certain diseases and pathogens.

Notes on Antibiotics

Antibiotic resistance is listed as one of the largest threats to humanity by the World Health Organisation, CDC etc. Bacteria and other pathogens are capable of resistance to a treatment on frequent exposure but bacteria being the most threatening. This has lead to many countries restricting their use, in countries like the UK they are only legal via prescription. Antibiotics unrestricted are commonly used without considering if the pathogen is actually a bacteria, if it is not it’ll have no effect but likely result in resistance of any bacteria around that are not currently a pathogen resulting in disease. In the aquarium there are many other treatments to try first. Antibiotics are reasonably specific to certain bacteria so would require knowing which are being targeted. If antibiotics are required then visit your vet, there are many fish vets within the UK who can be consulted on their opinion of the pathogen and course of treatment.

Pathogens of fishes and relevant articles to aid in diagnosis:

Spots, lumps and bumps: Click Here.

Sudden and rapid deaths (Unfinished)

Discolouration and change in skin/scale condition (Unfinished)

Abnormal external bodies (Unfinished)

References

Camargo, J. A., Alonso, A., & Salamanca, A. (2005). Nitrate toxicity to aquatic animals: a review with new data for freshwater invertebrates. Chemosphere, 58(9), 1255-1267.

Ciji, A., & Akhtar, M. S. (2020). Nitrite implications and its management strategies in aquaculture: A review. Reviews in Aquaculture, 12(2), 878-908.

Hanson, L., Dishon, A., & Kotler, M. (2011). Herpesviruses that infect fish. Viruses, 3(11), 2160-2191.

Hrubec, T. C., Smith, S. A., & Robertson, J. L. (1996). Nitrate toxicity: a potential problem of recirculating systems. Aquacultural Engineering Society Proceedings II: Successes and Failures in Commercial Recirculating Aquaculture. Northeast Regional Agricultural Engineering Service Cooperative Extension, Ithaca, NY.

Ip, Y. K., & Chew, S. F. (2010). Ammonia production, excretion, toxicity, and defense in fish: a review. Frontiers in physiology, 1, 134.

Khan, I., Saeed, K., Zekker, I., Zhang, B., Hendi, A. H., Ahmad, A., … & Khan, I. (2022). Review on methylene blue: Its properties, uses, toxicity and

Liu, M. J., Guo, H. Y., Liu, B., Zhu, K. C., Guo, L., Liu, B. S., … & Zhang, D. C. (2021). Gill oxidative damage caused by acute ammonia stress was reduced through the HIF-1α/NF-κb signaling pathway in golden pompano (Trachinotus ovatus). Ecotoxicology and Environmental Safety, 222, 112504.photodegradation. Water, 14(2), 242.

Lujan, N. K., Winemiller, K. O., & Armbruster, J. W. (2012). Trophic diversity in the evolution and community assembly of loricariid catfishes. BMC Evolutionary Biology, 12(1), 1-13.

Olufayo, M. O., & Yusuf, H. O. (2016). Toxicity of methylene blue on nile tilapia (Oreochromis Niloticus) juveniles. IOSR Journal of Environmental Science, Toxicology and Food Technology, 10, 9-16.

Piefke, T. J., Bonnell, T. R., DeOliveira, G. M., Border, S. E., & Dijkstra, P. D. (2021). Social network stability is impacted by removing a dominant male in replicate dominance hierarchies of a cichlid fish. Animal Behaviour, 175, 7-20.

Riley, R. J., Roe, T., Gillie, E. R., Boogert, N. J., & Manica, A. (2018). The development of social interactions in Corydoras aeneus larvae. bioRxiv, 455188.

Satoh, S., Tanaka, H., & Kohda, M. (2016). Facial recognition in a discus fish (Cichlidae): experimental approach using digital models. PloS one, 11(5), e0154543.

Walter, B., & Trillmich, F. (1994). Female aggression and male peace-keeping in a cichlid fish harem: conflict between and within the sexes in Lamprologus ocellatus. Behavioral Ecology and Sociobiology, 34, 105-112.

Yanong, R. P., Francis-Floyd, R., Curtis, E., Klinger, R. E., Cichra, M. F., & Berzins, I. K. (2002). Algal dermatitis in cichlids. Journal of the American Veterinary Medical Association, 220(9), 1353-1358.

Chaetostoma – The Coolest Plecos/Loricariidae

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I am personally most charmed by those Loricariids with unusual anatomy and none more then that dorso-ventrally compressed body shape. Most of these fishes enjoy high velocity water, living in the cracks and crevices of the rocks present, more then often not fishes you’d find around plants or even wood. Two genera come to mind when we think of this, Chaetostoma and Ancistrus although many more do exploit such a niche like Pseudolithoxus. Many genera we do not see in the trade though, these are largely members of that Chaetostoma clade; the paraphyletic Cordylancistrus, Andeanancistrus, Transancistrus and Leptoancistrus (Lujan et al., 2015).

This Chaetostoma clade have a unique appearance of long wide jaws and dermal plating stopping before the end of the head leaving a fleshy rim that lacks tentacles. The only taxa that look similar would be a few Ancistrus and the Neoplecostominae, Pareiorhapis but the latter displays quite reasonable hypertrophied odontodes and a much wider head. There is more precise skeletal anatomy to identify Chaetostoma (Lujan et al., but not really the easiest for the fishkeeper to identify.

As of 2022 there were 49 currently described species in the genus (Meza-Vargas et al., 2022) making Chaetostoma one of the numerous Loricariid genera excluding Ancistrus and Hypostomus all of which have many undescribed species. While in the aquarium trade we see very few with some rarities appear on occasion, the majority seem to be imported rather generally and therefore bycatch is not rare. This is one of the genera you can find something almost unseen in a general fish store due to this lack of identification. The most common being Chaetostoma formosae, C. sp. ‘L147’ and C. dorsale but Chaetostoma sp. L455/L457 is not unseen and has some amazingly striking patterning.

*Chaetostoma brevilabiatum* at Pier Aquatics

Chaetostoma has often been associated with being small but this genus represents some larger species such as Chaetostoma brevilabiatum growing to over 18cm Standard Length (SL) although most are around that 6/7cm SL mark (Lujan et al., 2015). They are notorious fast growers if in the right setup so certainly not one to forget about upgrading soon enough.

Habitat

While largely a hillstream or high velocity fish (In terms of our fishkeeping) they can be particularly widespread or less so depending on the species (Lujan et al., 2015). Ecology is rarely recorded as with many fishes where taxonomy has been the focus and while most descriptions come with coordinates that can be crosschecked against other information it is still somewhat making assumptions. Although for Chaetostoma chimu, C. formosae, C. dorsale, C. platyrhynchus and C. joropo all three are found in the same locality, explains mixed imports and we do have ecological records focused on C. chimu. The water is well oxygenated and by our aquarium standards has a high flow, temperatures of 21-29c, a pH of 7.1-8.9 along with a conductivity of 20.4–269.0 μS (Urbano‐Bonilla & Ballen, 2021) . This suggests fishes that experience quite a bit of variation and swings seasonally or maybe if there is frequent rainfall. Generally this does infer maybe a few species not difficult to house in captivity. That neutral pH is not uncommonly recorded, Chaetostoma spondylus is recorded from a habitat of a pH of 7.1 with again highly oxygenated water (Salcedo & Ortega 2015). Chaetostoma joropo also inhabiting highly oxygenated water at a pH of 7.1-8.6, a conductivity of 10.4–258.0 μS and temperatures of 21-30c. These are certainly not fish to keep at least at the high extreme but given the locality of many it seems particularly those at higher elevations would need much cooler water year round.

These habitats are extremely rocky with round boulders weathered from the flow of the rivers (Urbano‐Bonilla& Ballen, 2021; Meza-Vargas et al., 2022). Whether it be rocks, wood, pleco caves etc. plenty of hiding spots are a must for this genus.

Diet

While the habitat of Chaetostoma proves them adaptable their diet might not, these elongate jaws are extremely similar to other genera that have provided a challenge to aquarists e.g. Baryancistrus. The longer jaws with more numerous teeth are strongly associated with algivory (feeds on mostly algaes/aufwuch/periplankton; Lujan et al., 2012). Zúñiga-Upegui et al. (2017) is probably the most detailed paper on the diet of Chaetostoma although few ever discuss their diet, from their analysis the genus feeds almost entirely on algaes particularly diatoms. These diatoms are unlikely to be those highly stubborn ones to cause issues in the aquarium though.

If anything much like Baryancistrus this is a genus who would benefit from large amounts of algae’s in their diet whether it be Repashy soilent green with additional algal powders mixed in or In The Bag’s Pleco Pops. Many fish diets even most claimed as algae wafers contain very little and this genus has shown adaptable to these diets nutritionally I can’t see them being ideal.

Behaviour

I can’t argue for or against their territoriality as I haven’t seen it, even with any territorial species there is a benefit in others for enrichment given the right amount of space. Many fishes seem to learn feeding behaviours off each other.

Conclusion

Chaetostoma, it’s so unusual looking and can look creepy, they often get forgotten. These algivores who enjoy high flow and velocity would certainly make interesting tankmates in some of those aquariums which allow for such seasonal variation. Adaptable in parameters and maybe less so in diet is probably what defines the genus.

References/species descriptions:

Lujan, N. K., Meza-Vargas, V., Astudillo-Clavijo, V., Barriga-Salazar, R., & López-Fernández, H. (2015). A multilocus molecular phylogeny for Chaetostoma clade genera and species with a review of Chaetostoma (Siluriformes: Loricariidae) from the Central Andes. Copeia, 103(3), 664-701.

Lujan, N. K., Winemiller, K. O., & Armbruster, J. W. (2012). Trophic diversity in the evolution and community assembly of loricariid catfishes. BMC Evolutionary Biology, 12(1), 1-13.

Meza-Vargas, V., Calegari, B. B., Lujan, N. K., Ballen, G. A., Oyakawa, O. T., Sousa, L. M., … & Reis, R. E. (2022). A New Species of Chaetostoma (Siluriformes: Loricariidae) Expands the Distribution of Rubbernose Plecos Eastward into the Lower Amazon Basin of Brazil. Ichthyology & herpetology, 110(2), 364-377.

Salcedo, N. J., & Ortega, H. (2015). A new species of Chaetostoma, an armored catfish (Siluriformes: Loricariidae), from the río Marañón drainage, Amazon basin, Peru. Neotropical Ichthyology, 13, 151-156.

Urbano‐Bonilla, A., & Ballen, G. A. (2021). A new species of Chaetostoma (Siluriformes: Loricariidae) from the Orinoco basin with comments on Amazonian species of the genus in Colombia. Journal of Fish Biology, 98(4), 1091-1104.

Zúñiga-Upegui, P. T., Villa-Navarro, F. A., García-Melo, L. J., García-Melo, J. E., Reinoso-Flórez, G., Gualtero-Leal, D. M., & Ángel-Rojas, V. J. (2014). Aspectos ecológicos de< em> Chaetostoma sp.(Siluriformes: Loricariidae) en el alto río Magdalena, Colombia. Biota Colombiana, 15(2).

Bacterial Products for Cycling the Aquarium – A fish Biologists Perspective.

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This has to be one of the most hotly contested, almost every brand has their own product and if someone isn’t aligned with a brand they might have their own personal reputation weighing on their method. It’s worse when it comes to fish in or fishless cycling and that might be a whole other debate.

As a long term fishkeeper who’ve had fishes for a long time I’ve not needed to cycle a tank for a long time. I have plenty of media to cycle an aquarium and I go on a precaution of not enough for the fish I’m adding so I feed less and water change more to start with. For people reading this they are likely not new to fishkeeping so probably in the same field but maybe it means we are rusty on what to recommend? I actually ask is there a wrong and a right? I don’t think so.

When thinking about nitrification and realistically microbial colonies as it’s not just archaea and bacteria (Klotz et al., 2022). So commonly we might think of these as units and because we cannot see them we do not identify them for what they are, biological organisms and effected by the abiotic conditions and the other biological organisms around them. It is a whole ecosystem where they have to compete for particularly space and oxygen. Each nitrifying organism will have it’s own range of tolerance depending on strain and species but there will be much more generalist strains and species. When it comes to what bacterium and archaea are best for our aquariums might be known but so few products label what they contain.

The flaws of research

There is peer reviewed research into the topic (Scagnelli et al., 2023) and comparing brands but it is important to recognise particularly that the effects here are largely dependent on the actual methods. Are their study aquariums representative of what we keep as fishkeepers?

*Satanoperca* sp. possibly S. leucostictus

It is clear from the results that many of the bottled treatments did not differ from the control where they have no effect on ammonia concentration. Tetra’s bottled bacterial treatment has statistically significant results, decreasing the levels of ammonia over 14 days by 0.562 (+-0.08). This does mean that it still stands that these products vary (Scagnelli et al., 2023). Being scientific though and in the discussion of this topic it is worth critically analysing. The test kits were not mentioned and therefore the accuracy and reliability could be of question both regarding why the other products might not be displaying statistically significant results. It doesn’t seem to be mentioned the age of the products and how close to expiry they are.

It would not be fair to include unreliable experiments that lack peer reviewing.

Dr Tim’s One and Only

One of the most interesting brands, this is a scientist who has a good background in understanding nitrification as a microbiologist and a bibliography in the field. He is an aquarist as well which is of real value to the hobby, I feel in the UK his products have been a little forgotten.

There have been no reliable experiments or investigations into his products which makes them difficult to actually evaluate. While Dr. Hovanec has extensive experience in the field and his own products I guess the issue with him doing research that can get peer reviewed into his own products is conflict of interests. His research into the world of nitrification is particularly interesting.

Few brands as it is not required by law (as far as I know?) are likely to declare what strains and bacteria they contain to avoid competition. Burrell et al., (2001) suggested Nitrosomonas marina-like as a major contributor to nitrification while, Nitrosospira tenuis-like and Nitrosomonas europaea-like bacterium contribute to the mature aquarium. This paper was also contributed to by Dr Hovanec but Dr Tims as a brand was only started in 2007 and it’d make logical sense that the products would contain these strains. It’s not to say other brands do not contain these strains as the research is open access and it likely is that many do. In an earlier paper Nitrospira moscoviensis and Nitrospira marina were further confirmed to be contributors to nitrification but later studies on that mature aquarium were not conducted (Hovanec et al., 1998).

Of course this means brands are likely containing the right strains if did properly but concentrations would vary.

*Krobia xinegunesis* with *Corydoras granti* and *Cleithracara maronii*

So can they live that long?

One of the largest arguments is that the bacteria are all dead, this is quite weak as we know bacteria can go into hibernation for long periods of time when conditions are not ideal, not just when they are cold. Nitrifying bacterium are no exception and can survive long periods of time sealed (Alleman & Preston, 1991). Oxygen is a known cause for dormancy and therefore preventing death (Murphy et al., 2016), this assumes they are sealed without or very limited access to oxygen and many brands are able to provide this. Another aspect is when in the presence of other bacterium if they are not in this state it’s not difficult to see how they could be outcompeted or not survive.

Conclusion

Definitely not the longest discussion as it’s so personal. My personal criticism is there is no way someone can say x fish equals requiring x amount of product, it also depends what the fish is fed on.

I didn’t want to focus on any brands really as a criticism as it would be unfair given how little we know about them. While I do want to do personal experiments on the topic it would only be so reliable, the number of aquariums I’d need and to counter for so many variables.

It’s such a controversial topic and on top of that is social media. I personally think we should be open minded but critical about brands claiming to provide something while claiming other brands do not. That includes personal brands such as social media.

At the end of the day I feel cycle an aquarium how you want, there are too many knowns the discussion of fishless vs fish in entirely cannot be settled so that is another discussion. It’s very emotive as a topic. As a fish biologist I am not a microbiologist and therefore I think it’s worth making that clear.

References:

Alleman, J. E., & Preston, K. (1991). Behavior and physiology of nitrifying bacteria. In Proceedings of the second annual conference on commercial aquaculture, CES (Vol. 240, pp. 1-13).

Burrell, P. C., Phalen, C. M., & Hovanec, T. A. (2001). Identification of bacteria responsible for ammonia oxidation in freshwater aquaria. Applied and Environmental Microbiology, 67(12), 5791-5800.

Hovanec, T. A., Taylor, L. T., Blakis, A., & Delong, E. F. (1998). Nitrospira-like bacteria associated with nitrite oxidation in freshwater aquaria. Applied and environmental microbiology, 64(1), 258-264.

Klotz, F., Kitzinger, K., Ngugi, D. K., Büsing, P., Littmann, S., Kuypers, M. M., … & Pester, M. (2022). Quantification of archaea-driven freshwater nitrification from single cell to ecosystem levels. The ISME Journal, 16(6), 1647-1656.

Murphy, C., Rajabzadeh, A. R., Weber, K. P., Nivala, J., Wallace, S. D., & Cooper, D. J. (2016). Nitrification cessation and recovery in an aerated saturated vertical subsurface flow treatment wetland: Field studies and microscale biofilm modeling. Bioresource technology, 209, 125-132.

Scagnelli, A. M., Javier, S., Mitchell, M., & Acierno, M. (2023). Efficacy of quick-start nitrifying products in controlled fresh-water aquaria. Journal of Exotic Pet Medicine, 44, 22-26.

Leporacanthicus and Scobinancistrus: A dietary guide to molluscivorous Loricariids.

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While the majority of Loricariids are algivores/detritivores (Lujan et al., 2012), there is a number of those who are carnivorous and even less likely specialise in molluscs.

Figure 1: *Scobinancistrus auratus* at Maidenhead Aquatics, Ascot.

Scobinancistrus and Leporacanthicus are both genera in the subfamily Hypostominae of the Siluriforme (catfish) family, Loricariidae. Scobinancistrus is nested within the Peckoltia group while Leporacanthicus places within the Acanthicus group (Fig 2). As a result these two species are not closely related at all, making the molluscivorous dietary niche convergent.

Figure 2: Phylogeny of the Peckoltia group from: Lujan, N. K., Armbruster, J. W., Lovejoy, N. R., & López-Fernández, H. (2015). Multilocus molecular phylogeny of the suckermouth armored catfishes (Siluriformes: Loricariidae) with a focus on subfamily Hypostominae. *Molecular phylogenetics and evolution*, 82, 269-288.

Both genera are reasonably small in size, Leporacanthicus contains four described species: L. galaxias (Galaxy/vampire pleco/L007/L240), L. joselimai (Sultan pleco/L264), L. heterodon (Golden vampire pleco) and L. triactus (Three becon pleco/L091); Scobinancistrus contains three described species: S. auratus (Sunshine pleco/L014), S. pariolispos (Golden cloud pleco/L133) and S. raonii (L082). There are multiple undescribed species or variant’s in both genera. Species descriptions are included in the reference list.

Neither of these genera are particularly small in size particularly Scobinancistrus where both S. pariolispos, S. auratus and the undescribed species grow to 30cm SL, S. raonii being an exception at 22cm SL (Chaves et al., 2023). On the other hand Leporacanthicus while the Acanthicus group represents the largest species is generally around 24cm SL (Collins et al., 2015) with the exception of Leporacanthicus joselimai at around 15cm SL (Isbrücker & Nijssen, 1989). So these are not the smallest of fishes but generally the scientific literature includes much smaller sizes then some of the images of fishes obtained from the wild.

When we look at habitats for this clade it is generally always rocky with little to no macrophyte plants, these fishes enjoy a good current (Chaves et al., 2023; Isbrücker & Nijssen, 1989; https://amazonas.dk/index.php/articles/brasilien-rio-xingu). This is partially a clue to why their morphology is the way it is. Particularly those Rio Xingu species e.g. Scobinancistrus auratus, S. raonii and Leporacanthicus heterodon will not experience temperatures below 28c (Rofrigues-Filho et al., 2015).

While juveniles are not noted to be a particular issue unlike the majority of the Acanthicus clade both can be particularly territorial with age. I have a clear memory of a Leporacanthicus breeder explaining how a pair couldn’t be housed with other Loricariids due to the level of aggression. In a larger aquarium with plenty of caves and decor to break up the tank could work but this has to be taken into consideration for the future.

Figure 3: *Scobinancistrus aureatus* at Maidenhead Aquatics, Ascot.

Dietary niche

Both of these genera have very specialist jaws, they are particularly agile to move around or into a food item as displayed in figure 3. This mobility of the soft oral suction cup-like mouth is to more of an extreme then other carnivores; Pseudacanthicus who is much more general as a carnivore.

Figure 4: *Leporacanthicus galaxias* from: https://www.suedamerikafans.de/wels-datenbank/maulstudien/

Leporacanthicus goes a little more further with a particularly large, fleshy with many particularly large unculi.

Figure 5: The jaws of *Leporacanthicus* sp. as featured in: Lujan, N. K., Winemiller, K. O., & Armbruster, J. W. (2012). Trophic diversity in the evolution and community assembly of loricariid catfishes. *BMC Evolutionary Biology*, 12(1), 1-13.

If anything talks about diets so much, it is the skeletal anatomy and the jaws (Fig 5). These two genera have very robust jaws but other Loricariids particularly Hypostominae have this, what separates Scobinancistrus and Leporacanthicus is the area around the tooth cup. It is extremely elongate downwards, protruding but unlike other Loricariids it is also very limited for teeth (Fig 5).

The teeth are very few and sparse, which correlates with carnivory (Lujan et al., 2012). These teeth being strong, maybe due to colouration maybe mineralised and, more then anything long.

Their diet

These fish are adapted for reaching into something so……..molluscs……..

The interesting thing about diets is for quite a lot of species we don’t entirely know what they eat. Gut analysis is still the most common method of analysing animal diets but that only shows a snapshot of what is in their gut at that time but ignores seasonal variance or digestion. Hence Panaque being a particular curiosity, few organisms can digest wood were studied further but others it’s not looked further. Often with fishes only a small number of individuals are used which can limit it further. When thinking functionally half of diet is what they eat the rest is where they eat, like it’s fine to eat invertebrates, many animals do but to extract it from an object is another, you can’t compare their morphology.

The suggestion of these fishes feeding on molluscs is not old (Black & Armbruster 2022), other groups e.g. fishes are confirmed to feed on molluscs but morphologically nothing similar. Morphology doesn’t mean molluscs are not their diet as molluscs can be in difficult to reach areas.

The description of Scobinancistrus raonii was the most detailed of their diets inferring the use of invertebrates, algaes and porferia (I know an invertebrate; Chaves et al., 2023). Porferia is not a rare mention in the scientific literature as a Loricariid diet as featuring in the diet of Megalancistrus aculeatus but based on dietary analysis (Delariva & Agostinho, 2001). Sponges are a discussion that would need analysing further, Professor Donovan P. German, a scientist specialising in fishes diets discusses that previous fishes that specialise in sponges do so similar to Panaque, they break down the sponges in search of things they can digest. So I will illude suggestions they can digest sponges, either way not a viable diet in captivity as sponges take so long to grow.

Personal experience only hold up so much ground but I have experienced both take particular interest in molluscs and extracting them from their shells, unlike other taxa they cannot crush those shells. Their jaws and teeth even just suggest how they cannot crush, look at your own teeth, your crushing teeth are rounder and shorter.

We don’t really know if they do eat molluscs, the bodies of molluscs wont appear on gut analysis as easily processed. I don’t know yet enough about isotope analysis to test other methods. But if they show the interest it’s something to explore.

The other avenue is these long jaws and teeth are for extracting things from the cracks and crevices in wood.

Either way though we don’t have the captive diets to really cater carnivory that well yet so no harm in the snails but look at a diet that is based on invertebrates. They show an interest in molluscs so those without the trapdoor would be amazing.

In Loricariidae there is the new frontier in diets, places to explore and understand. We do not know yet so worth looking further. We are miles from the answer in what they really digest and eat.

References:

Black, C. R., & Armbruster, J. W. (2022). Chew on this: Oral jaw shape is not correlated with diet type in loricariid catfishes. Plos one, 17(11), e0277102.

Collins, R. A., Ribeiro, E. D., Machado, V. N., Hrbek, T., & Farias, I. P. (2015). A preliminary inventory of the catfishes of the lower Rio Nhamundá, Brazil (Ostariophysi, Siluriformes). Biodiversity Data Journal, (3).

Delariva, R. L., & Agostinho, A. A. (2001). Relationship between morphology and diets of six neotropical loricariids. Journal of Fish Biology, 58(3), 832-847.

Lujan, N. K., Armbruster, J. W., Lovejoy, N. R., & López-Fernández, H. (2015). Multilocus molecular phylogeny of the suckermouth armored catfishes (Siluriformes: Loricariidae) with a focus on subfamily Hypostominae. Molecular phylogenetics and evolution, 82, 269-288.

Lujan, N. K., Winemiller, K. O., & Armbruster, J. W. (2012). Trophic diversity in the evolution and community assembly of loricariid catfishes. BMC Evolutionary Biology, 12(1), 1-13.

Rios-Villamizar, E. A., Piedade, M. T. F., Da Costa, J. G., Adeney, J. M. and Junk, W. J. (2013). Chemistry of different Amazonian water types for river classification: A preliminary review. Water and Society 2013, 178.

Species descriptions:

Burgess, W. E. (1994). Scobinancistrus aureatus, a new species of Loricariid Catfish from the Rio Xingu (Loricariidae: Ancistrinae). TFH Magazine. 43(1):236–42.

Chaves, M. S., Oliveira, R. R., Gonçalves, A. P., Sousa, L. M., & Py-Daniel, L. H. R. (2023). A new species of armored catfish of the genus Scobinancistrus (Loricariidae: Hypostominae) from the Xingu River basin, Brazil. Neotropical Ichthyology, 21, e230038.

Isbrücker I. J. H. and Nijssen H. (1989). Diagnose dreier neuer Harnischwelsgattungen mit fünf neuen Arten aus Brasilien (Pisces, Siluriformes, Loricariidae). DATZ. 42(9):541–47

Isbrucker, I. J., Nijssen, H., & Nico, L. G. (1992). Leporacanthicus triactis, a new loricariid fish from upper Orinoco River tributaries in Venezuela and Colombia (Pisces, Siluriformes, Loricariidae). Die Aquarien-und Terrarienzeitschrift (DATZ), 46(1), 30-34.

Hypancistrus – A Dietary Guide to the Fancy Pleco

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Figure 1: *Hypancistrus zebra* (Zebra pleco, L046)

Hypancistrus is a relatively medium sized genera with a type species of Hypancistrus zebra (Fig 1). The genus is nested within the Peckoltia clade in the subfamily Hypostominae (Fig 2) and displays similar morphology to many members of this group.

Figure 2: Phylogeny of the Peckoltia clade: Lujan, N. K., Cramer, C. A., Covain, R., Fisch-Muller, S., & López-Fernández, H. (2017). Multilocus molecular phylogeny of the ornamental wood-eating catfishes (Siluriformes, Loricariidae, Panaqolus and Panaque) reveals undescribed diversity and parapatric clades. *Molecular phylogenetics and evolution*, *109*, 321-336.

The body shape of Hypancistrus is generally quite characteristic of many typical Hypostominae plecos. They tend to have a shorter head and larger eyes compared to Panaqolus and Peckoltia. Markings are spotted or striped but vermiculations are present, these might reduce with age or change shape. Colouration similarly becomes less distinctive with age but the majority of members are white/yellow and grey/black.

Like the majority of the Peckoltia group Hypancistrus displays hypertrophied (large) odontodes (external teeth, not used for feeding) on the caudal peduncle, pectoral fin spines and at the gill opercula. These odontodes are sexually dimorphic being hypertrophied in the caudal peduncle and pectoral fin spines within males while females also absent. In mature males the odontodes that cover the body tend to become larger giving a more blurred appearance to the fish (Reis et al., 2022).

Regardless of the popularity of the genus Hypancistrus, there are only 9 described species (Fricke et al., 2023) but almost four times that are undescribed with and without L numbers. This doesn’t define if these undescribed individuals are species as L066 and L333 has been suggested to be the same species (Cardoso et al., 2016).

Hypancistrus is generally located within areas of high velocity water residing between the cracks and crevices. Water temperatures are a minimum of 28c and this is why flow within captivity is important to keep oxygen levels high (de Sousa et al., 2021).

The Ecomorphology of Hypancistrus

Figure 4: *Hypancistrus* sp. L333, the image is from the amazing website: https://www.suedamerikafans.de/en/wels-datenbank/maulstudien/?cookie-state-change=1701028628501 Great for anyone wanting to look at mouths of Loricariids and other information.

Ecomorphology are anatomical traits that are involved in functional behaviour such as feeding. This oral morphology (Fig 4) is very similar to particularly Peckoltia itself. There are a reasonable amount of teeth particularly on the maxaillae, upper jaw and less on the dentary, lower jaw. While there are a few it is a lot more then the closely related, carnivorous Scobinancistrus. The jaws of Hypancistrus are strong and robust, very similar again to Peckoltia but not quite the same as the other closely related genus, Panaqolus.

Dietary Ecology

Hypancistrus is often recorded as being a carnivore, I don’t entirely know where the assumption comes from but it must stem from this common idea that any of the colourful Loricariids are, I have seen this stated quite frequently. Additionally maybe the doctorial thesis of Dr. Jansen Zuanon where the species Hypancistrus zebra is suggested to feed on reasonable amounts of Bryozoa along with algaes (Zuanon, 1999). As many things do with time information is lost, some older information generalises the genus as omnivores and later others have suggested carnivores.

When reading the scientific literature including Zuanon (1999) there is limited references to the diet of Hypancistrus. There is gut analysis attached to the description of four species. While various algae and detritus made up the majority of the gut contents of these four species: numerous processed seeds were located in the gut of Hypancistrus inspector (Armbruster, 2002), bryophytes (mosses) within Hypancistrus lunaorum and; in Hypancistrus contradens in addition to mostly algae and detritus, some aquatic invertebrates were located (Armbruster et al., 2007). This infers that Hypancistrus is some what of a generalist but likely more on the herbivorous side.

So what should you feed Hypancistrus in captivity?

Don’t forget those algae’s, a diet with a range and high amounts of these algae’s will be beneficial. Always check ingredient lists, algae’s unlike many macrophyte plants are high in protein and various vitamins and minerals. As the fish are evolved to feed on these it’ll be much more easy for them to digest and less waste produced as a result. In addition a little bit of variation, the odd frozen food such as brine shrimp, tubifex etc. would not be bad but many diets that contain algaes also contain this. Mosses would be an interesting addition to trial, aquarium mosses can be quite expensive but perhaps terrestrial mosses from areas without pesticides?

Of all the things to trial seeds, as mentioned by Armbruster (2002), at least Hypancistrus inspector feeds on seeds. This is certainly worth exploring with many more Loricariids and a variety of seeds as bare in mind the number of plants that produce seeds is immense, fruits that contain seeds such as blueberries and pomegranate could be worth trying. They might not jump to them but it’s worth sitting back and watching, in discussion with other fishkeepers seeds have been worth the trial. As seeds are almost a storage body for many plants they will contain a lot of nutrition and could explain why Hypancistrus and maybe Peckoltia have such strong jaws. A selective advantage at a seasonal or occasional food item? Selective advantages towards awkward to reach food items are not rare in Loricariidae.

Conclusion

Hypancistrus might be popular for their colours, their patterning but ecologically they offer quite a lot that has yet to be explored. The focus on breeding them has maybe moved the husbandry of the genus away from a curiosity of just keeping them and understanding them.

References:

Armbruster, J. W. (2002). Hypancistrus inspector: a new species of suckermouth armored catfish (Loricariidae: Ancistrinae). Copeia, 2002(1), 86-92.

Armbruster, J. W., Lujan, N. K., & Taphorn, D. C. (2007). Four new Hypancistrus (Siluriformes: Loricariidae) from Amazonas, Venezuela. Copeia, 2007(1), 62-79.

Cardoso, A. L., Carvalho, H. L. S., Benathar, T. C. M., Serrao, S. M. G., Nagamachi, C. Y., Pieczarka, J. C., … & Noronha, R. C. R. (2016). Integrated cytogenetic and mitochondrial DNA analyses indicate that two different phenotypes of Hypancistrus (L066 and L333) belong to the same species. Zebrafish, 13(3), 209-216.

Fricke, R., Eschmeyer, W. N. & Van der Laan, R. (eds) 2023. ESCHMEYER’S CATALOG OF FISHES: GENERA, SPECIES, REFERENCES. (http://researcharchive.calacademy.org/research/ichthyology/catalog/fishcatmain.asp)

Lujan, N. K., Cramer, C. A., Covain, R., Fisch-Muller, S., & López-Fernández, H. (2017). Multilocus molecular phylogeny of the ornamental wood-eating catfishes (Siluriformes, Loricariidae, Panaqolus and Panaque) reveals undescribed diversity and parapatric clades. Molecular phylogenetics and evolution, 109, 321-336.

Reis, R. G. A., Oliveira, R. S. D., da Silva Viana, I. K., Abe, H. A., Takata, R., de Sousa, L. M., & da Rocha, R. M. (2022). Evidence of secondary sexual dimorphism in King Tiger Plecos Hypancistrus sp, Loricariidae, of the Amazon River basin. Aquaculture Research, 53(10), 3718-3725.

Catfish fans – Southamerica fans

de Sousa, L. M., Lucanus, O., Arroyo-Mora, J. P., & Kalacska, M. (2021). Conservation and trade of the endangered Hypancistrus zebra (Siluriformes, Loricariidae), one of the most trafficked Brazilian fish. Global Ecology and Conservation, 27, e01570.

Zuanon, J. A. S. (1999). História natural da ictiofauna de corredeiras do rio Xingu, na região de Altamira, Pará.

The Myth of Female Aggression: A Focus on Territoriality in Loricariids (Pleco’s) Catfishes.

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Men are from Mars and Women are from Venus, Mars the roman god of war and Venus the Roman goddess of love and fertility. Males of a species are often associated with aggression and self determination; females associated with passivity and a peaceful nature. Species such as the Spotted Hyena (Crocuta crocuta) that so obviously turn this view upside down are often of curiosity.

Misconceptions of female aggression are common throughout all vertebrates for various reasons. Within horses one mare determines where the rest of the group are going and the others can determine if to tolerate the male or not. They show a range of different aggressive behaviours between each other and towards males (Curry et al., 2007), hierarchy is as important in the females in a group as it is for males. It’s not all about reproduction but social positioning can effect a females chance as it does for males.

Cichlid Aggression

Cichlids are well known for aggression, perhaps it is a bit overemphasized as their behaviour is much more complex then just needless aggression. It is also a vast grouping where levels of aggression and territoriality vary along with the reasons for. And like Loricariids there are social species and more solitary species, juveniles of any will spend a considerable amount of time in a gregarious state (Forsatkar et al., 2016).

Territoriality is common in cichlids where both males and females defend a space particularly if spawning. In species with large size disparity the females contribution might be easily forgotten yet keep a female alone regardless of the presence of eggs and it is notable she is not a passive individual. In hareming species such as many Apistogramma or the shelldwelling Neolamprologous males hold a larger territory. The females are not shoaling passively, they each hold their own territory within the males defending from other females and sometimes keeping the male within a reasonable distance should there be fry and eggs. Interestingly males play a role in mediating aggression between females (Walter & Trillmich, 1994), this is a role I have seen in other animals where the mixture of sexes reduces overall aggression.

The Siamese Fighting Fish, Betta splendens

This species has been the objects of fascination for many for the males beautiful morphology and their territorial behaviour. While the males have often been the highly valued fishes, females are seen as a side addition. Neither sex is social in the wild, these are largely solitary, territorial fishes so the benefit of keeping females in a group is only that of the owners. Females are shown to be equally as aggressive as males with similar aggressive behaviours (Braddock & Braddock, 1955). Where females are not known for aggression likely stems from the majority of these being plakat, short finned whereas many males are long finned and therefore will struggle with any territorial interactions.

Although it could be argued in a sufficiently big enough tank multiple individuals of both sexes could provide social enrichment assuming they can all develop their own territory. I would largely only advice keeping individuals alone unless spawning, there are social species of Betta that might be a better option for some.

I have worked with and kept a lot of Betta splendens, they are a staple of the aquarium trade and if anything can be a problem is sorority setups. Due to the amount of tanks needed to store individuals only males and the most fancy females could be housed alone. In these sorority tanks there was always a high rate of injuries between individuals, some variants were worse then others, particularly long finned females. In store setups it’s quite easy to experiment and increasing the amount of decor or adding in a variety of different tankmates did not reduce these aggressive interactions.

Why might females display aggression?

Sociality, even a gregarious species will have many complex interactions between individuals. Maintaining ones place within a shoal hierarchy is a common cause for aggression.
Territoriality, maintaining a space in which might contain resources such as food or the best spawning caves. Aggression to defend an item of food is common because this will aid in them maintaining a good condition.
Reproduction, sometimes females will defend the offspring from other species, individuals or even the male.

Loricariid (pleco) aggression

Loricariidae is a 1,051 species strong family of fishes so they cannot easily be generalised. There are both gregarious and territorial species within this gigantic clade. Generally Hypoptopominae are social and gregarious, Rinelepinae I have not heard of aggression from this strange subfamily. Deluturinae and Lithogeninae are subfamilies which never reach the aquarium trade so easily can be ignored here. This leaves the two largest subfamilies, Loricariinae and Hypostominae.

Loricariinae (Whiptail catfishes), the majority of these are social such as Farlowella (twig catfish), Sturisomatichthys (royal whiptail), even those which are not the steryotypical pleco/Loricariid like Rineloricariae. Although some species like Planiloricaria cryptodon can be particularly aggressive, it’s not entirely clear why, these are a species that spawns using their amazing barbels so not need to defend a spot. It is not sex specific but in caring for them around maturity they really need a larger tank or one per a tank.

Hypostominae, the largest subfamily with over 500 species. The majority of fishkeepers keep juvenile and with their illusive behaviour many interactions are easily missed. There is only a small number of gregarious species in this subfamily who lack any territorial tendencies e.g. Ancistrus ranunculus. Hypostominae are far from peaceful in general, sometimes fearsely defending an area from congeners (Hossain et al., 2018).

*Hemiancistrus subvirdis* (Green Phantom Pleco, L200) at Acres Aquatics, Wiltshire.

Hypostominae are crevice spawners in which a male defends a cave when there are fry or eggs within the space (Secutti, S., & Trajano, 2009). Although this doesn’t mean females do not express any aggression, both are territorial and will defend their space from any similarly shaped and sized fishes. It’s not difficult to understand why, as these fishes are likely defending food resources and the best caves to hide from predators regardless if used for spawning. The best grazing spots for many species are probably quite highly prized. Females are only spawning for short periods of time as play no role in brood care (Mendes et al., 2018), but as a result unlike males they tend to roam much larger areas, regarding aggression this poses a larger issue to the fishkeeper.

Some genera display much higher levels of aggression then others, the Acanthicus clade is particularly noted for aggression even in juveniles Pseudacanthicus will rasp on each other. Hypostominae are not loyal with their pairs although fishkeepers have noted aggression towards other fishes of both individuals in a pair preventing other fishes being added. I myself have quite a few mature Baryancistrus, in which the females I’ve seen lunge at other fishes, ram others into caves and intense shoving matches. In the common bristlenose, an Ancistrus, two mature females where this shoving match resulted in serious injuries. I have worked with an adult female Hypostomus luteus who couldn’t be housed with any other fishes within the restricted space of an aquarium after chasing many Pterygoplichthys non-stop.

Juvenile *Pseudacanthicus serratus* (Black mustang pleco)

Aggression is not restricted to males and for many species they are not easy to sex so for the majority of fishkeepers they would not know whether this fish is male or female. They are fishes who enjoy having their own space so plenty of caves and the space needed, it doesn’t mean multiple species can’t be kept together it just means consideration is needed. Aggression is also not limited to being intrasexual as individuals of different sexes will also display aggressive behaviours when not spawning.

The issue with Loricariidae is outside their phylogenetics and taxonomy we don’t know an awful lot about them so there is little research into their behaviour and the causes of territoriality between the two sexes.

Conclusion

Aggression is found throughout many clades of fishes and there are many different triggers for this behaviour. Where a male is aggressive it’s likely the females will be too and sometimes much more then those males.

References:

Braddock, J. C., & Braddock, Z. I. (1955). Aggressive behavior among females of the Siamese fighting fish, Betta splendens. Physiological Zoology, 28(2), 152-172.

Curry, M. R., Eady, P. E., & Mills, D. S. (2007). Reflections on mare behavior: Social and sexual perspectives. Journal of veterinary behavior, 2(5), 149-157.

Forsatkar, M. N., Nematollahi, M. A., & Bisazza, A. (2016). Quantity discrimination in parental fish: female convict cichlid discriminate fry shoals of different sizes. Animal cognition, 19, 959-964.

Hossain, M. Y., Vadas Jr, R. L., Ruiz-Carus, R., & Galib, S. M. (2018). Amazon sailfin catfish Pterygoplichthys pardalis (Loricariidae) in Bangladesh: a critical review of its invasive threat to native and endemic aquatic species. Fishes, 3(1), 14.

Mendes, Y. A., Lee, J. T., Viana, I. K., Rocha, R. M., & Ferreira, M. A. (2018). Reproductive biology of the tiger pleco Panaqolus tankei (Loricariidae) in a lentic system of the Amazon Basin. Journal of Fish Biology, 93(4), 711-714.

Secutti, S., & Trajano, E. (2009). Reproductive behavior, development and eye regression in the cave armored catfish, Ancistrus cryptophthalmus Reis, 1987 (Siluriformes: Loricariidae), breed in laboratory. Neotropical Ichthyology, 7, 479-490.

Catering for Algivores/detritivores.

Catering for Carnivores.

Other niches and specialization.

Will they eat it?

Premade diets and their ingredients

The hidden issue with premade diets

Products sold for plecos

Morphology

The complexity of dietary specialization

Habitat and setup

Sociality

Identification

Conclusion

What colour should my lights be?

How long should lights be on? If at all?

White spot/ich (Ichthyophthirius multifiliis)

Velvet (Oodinium, Piscinoodinium and other dinospores) and related taxa

Dermocystidium

Worm cysts

Tumors

Viral papilloma and herpes viruses

Unknown growths

Preventative care to avoid disease

What are pathogens?

Disease and pathogen specificity.

Notes on Antibiotics

Pathogens of fishes and relevant articles to aid in diagnosis:

References