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.

1. Catering for Algivores/detritivores.
2. Catering for Carnivores.
3. Other niches and specialization.
4. Will they eat it?
5. Premade diets and their ingredients
6. The hidden issue with premade diets
7. Products sold for plecos

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 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

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.

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

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.

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

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.

When people think of plecos they think of the term ‘suckermouth catfish’, yet these are the total exception with little to no ability to attach to any surface.

Here I am referring to those Loricariids who spend their time largely on the substrate often with their ornate mouths with many long and short barbels also known as cirri (Rojas-Molina et al., 2019). Unlike most other Loricariids, plecos these fishes are not crevice spawners and in some species the ornate cirri are used by the males to hold the eggs (Corvain & Fisch-Muller, 2007). There is one exception here, I tend to classify Isorineloricaria and Aphanotorulus (previously known as Squaliforma) and largely known as the Thresher plecos, these are in the subfamily Hypostominae where the majority of well known Loricariids, plecos place. While the majority of this category are in the subfamily Loricariinae often known as whiptail catfish.

So this is not so much a nutritional, dietary category as much as to where they feed and to me that makes a massive difference. Scientifically there isn’t the greatest understanding of this group either but hopefully with future advances in the coming years we can. So obviously I will have to edit this one day.

Many of these species forage and locate food by processing the substrate a bit like Panaque process wood in search of their food. Using their jaws they filter food objects from that substrate. All of these species really need a sandy substrate, not just because many need to hide in it but also the enrichment of naturally removing food from it.

There are both algivores/detritivores and carnivores in this category. Ofcourse I definitely recommend reading my article on algivores and detritivores but their mode of feeding limits a lot.

What genera are in this category?

• Aphanotorulus (Squaliforma): Generalist detritivore
• Crossoloricaria
• Hemiodontichthys acipenserinus: Maybe a carnivore?
• Isorineloricaria: Likely generalist detritivore.
• Loricaria
• Planiloricaria cryptodon: Either carnivore or feeds on seeds.
• Pseudohemiodon: Suggested to be periplakton and algaes but could also feed on seeds.
• Reganella
• Rineloricaria (To an extent): Not exactly purely the substrate but do interact a lot with it.

There isn’t that many and I think this niche in many habitats are often catered for by other groups of fishes.

Anything these fishes feed needs to sink but that’s usually a given for Loricariids and ideally not large food items. Some of these genera have few to any teeth and very small jaws so cannot break into large food items. I’m not even sure we entirely know the actual mode of feeding they use and for research they are not the cheapest to obtain. For Isorineloricaria and Aphanotorulus their jaws are large and strong so it doesn’t make the largest amount of difference.

There are multiple genera here with morphology/anatomy that is unexplained, split between granivores (Seeds) or potentially molluscivorous (Gastropods like snails and bivalves) we just don’t know. We do know from a previous article that hardness of food items can matter so I think either way providing both would be beneficial, seeds such as from non-citrus fruits or apples, such as blue berries. Pest snails, no harm in having them as suggested in my snail article they can be a benefit. These are great snails for such species as easy for them to break down with the pharyngeal jaws.

When it comes to carnivores their interaction with the substrate does hint to them feeding on those invertebrates such as annelids and insect larvae that spend a considerable amount of time there.

It’s so difficult as we are making a lot of assumptions as to what they are eating and here I will treat them as the same. There is likely a lot of overlap at least. So as per the previous article into algivores and detritivores I highly recommend a good basic diet to build off. This will provide the essential nutrition to work off.

Anyway suggested basis diets:

• Repashy Soilent Green and Bottom scratcher: Large diversity of algaes and high amounts of these algaes in Soilent Green. Bottom Scratcher on the other hand is very high in invertebrate items. They are higher up the list of ingredients so make up a lot of these diets. Easy to access for the majority of the world with many distributors. A gel diet so can be mixed to different consistencies and cooked to a jerky. It sinks and is very easy to break apart even if large by many of these species. The issue is what to which species if their diet is unknown.
• In The Bag, Tropical Fish UK, Pleco Pops! Algae Grazer or Crickie-Dough: Over 75% algaes which is a very high amount for the algae based diet. The Crickie-Dough is even better I’d argue then bottom scratcher as high in crustaceans which is what most of these fishes would eat in the wild. While Repashy Bottom scratcher does provide a mollusc it is not closely related to gastropods or bivalves. Also a gel diet, the gelling agent used is brilliant as holds for an extremely long time, over 24 hours which is longer then any other gel food or one you can make your own. Cocoa powder is one is the most interesting and brilliant ingredients!
• New Life Spectrum, Algaemax: Not to be confused with others of the same name so check the ingredients. Does contain a lot of algal ingredients but I can’t comment further due to UK availability.
• C.E Essentials, Naturekind: While aimed at discus, Symphysodon it does contain a lot more algaes then other diets.
• Should you make your own? You can but and that is a big but narrowing down the gelling agent that can last a few hours. This is difficult and takes time. Making your own diet commands research into nutrition and I’m really just only a beginner I think in that. It’s a large initial financial input as the ingredients particularly algaes are not cheap. This might be the only solution for some people in many countries and it is a debate for me how to help there.

Now to additions or supplements:

Frozen foods: A diversity of them would be brilliant so they can really feed off the substrate. Avoiding mussels as high in thiaminase and deficient in thiamine.

Live foods: Avoid any that move around the water column but those that focus in the substrate would be brilliant and offer more natural enrichment particularly black worms and tubifex.

Nori: Once it’s no longer a sheet I’d be inclined to suggest this as it rests in the substrate eventually, maybe not the best.

Earthworms: For larger species these might be found at the reptile store under the name Dendrobaena but definitely not to be missed. Do not forget though as they can survive underwater for some time if left and forgotten.

This sounds like a very limited list but compared to traditional algivores and detritivores frozen foods alone offers a lot more!

References:

Covain, R., & Fisch-Muller, S. (2007). The genera of the Neotropical armored catfish subfamily Loricariinae (Siluriformes: Loricariidae): a practical key and synopsis. Zootaxa, 1462(1), 1-40.

Rojas-Molina, Y. A., Provenzano-Rizzi, F., & Ramírez-Gil, H. (2019). A new species of whiptail armored catfish, genus Pseudohemiodon (Siluriformes: Loricariidae) from the Orinoco River basin, Llanos region of Colombia and Venezuela. Neotropical Ichthyology, 17, e180160.

This is a seriously large topic with 1,050 species according to Catalog of Fishes, so it’s not a simple answer. The majority of Loricariids are algivores and detritivores (Lujan et al., 2012). Even within detritivory and algivory there is partitioning (Lujan et al., 2011), this does mean they will not be feeding on the same thing. There is little research if to whether their diet changes with age but it seems there might be slight changes, certainly not towards any omnivorous/carnivorous diet as adults still had algae within their gut (Nonogaki et al., 2007), there is although evidence for seasonal shifts in diet (Mazzoni et al., 2010).

Here as I cannot really discuss all species and we are still in early days of understanding Loricariid diets I will present different categories with diets and suggestions to further supplement their diet.

Contents:

1. Algivores/Detritivores
2. What brands can I recommend as this basis to the diet, the foundations?
3. What genera are included in this (off the top of my head)?
4. Quick comment on wood ‘eaters’
5. So lets discuss supplements and additions to further cater for these fishes diets.
6. Gut Biota, what and why?
7. References:

Algivores/Detritivores

It’s almost impossible to separate algivores and detritivores when it comes to Loricariids as there is so much overlap between the two categories but of course there is partitioning. It’s just we can’t really entirely cater for that partitioning. A lot of what is contained within detritus is this matrix of bacteria, protozoa, algaes and other microbes. In addition there are species who will feed more on algaes and some certain algaes like cyanobacteria e.g. Lasiancistrus caucanus (potentially L. mayoloi; Valencia & Zamudio, 2007), while others who might focus more on bacteria or fungi. We really don’t entirely know how much subdivision there is beyond the fact it exists. This is maybe the most fascinating dietary category as few other groups of fishes can do it like Loricariids can.

So, this category fills up the majority of Loricariids (Lujan et al., 2012) yet is maybe the most misunderstood or catered for. Bacteria, protozoa and other microbes are not really available in any commercial diets or even as ingredients which is very limiting leaving just algaes. We do know algaes are great in nutrition given just one species of algae replaced the nutritional requirements of a commercial diet which contained fish meal, cereals but only very few algaes in small volumes (Vucko et al., 2017).

The common misconception is that algaes are low in protein, yet they can be very high (Chen et al., 2022). This misconception comes from their similarity to plants but only green algaes are closely related to plants, while the term algae includes many other groups e.g. spirulina which is a cyanobacteria. Plants used in fish feeds might even lack many essential amino acids or contain anti-nutritional factors (Trevi et al., 2023). Algaes aren’t just high in protein but also very high in vitamins, minerals and essential fatty acids, to top the list of why algaes are great is their benefits on fish pigmentation (Alagawany et al., 2021; Trevi et al., 2023; Chen et al., 2022). So certainly an ingredient that shouldn’t be forgotten.

As we are talking fishes that feed on algaes as a large amount of their wild diets I can’t see how these simple ingredients are not useful. There is the issue of palatability and I have largely noticed they might struggle to recognise food not growing on a surface so in a wafer or pellet as algaes hence some taxa like those which are carnivores seem to do better then the very strict algivores.

So all we have to go off is a very small set of algaes but what should you look for in a main staple diet?

A main diet is what I see as the foundations of any fish food, this will contain all the main nutrition, vitamins and minerals. I understand additionally that different foods are limited around the world and cost also varies which makes it incredibly difficult for this dietary group.

What brands can I recommend as this basis to the diet, the foundations?

• Repashy Soilent Green and Repashy Super Green: Large diversity of algaes and high amounts of these algaes, I believe 80% in Super Green. They are higher up the list of ingredients so make up a lot of these diets. Easy to access for the majority of the world with many distributors. A gel diet so can be mixed to different consistencies and cooked to a jerky.
• In The Bag, Tropical Fish UK, Pleco Pops: Over 75% algaes which is a very high amount. Also a gel diet, the gelling agent used is brilliant as holds for an extremely long time, over 24 hours which is longer then any other gel food or one you can make your own.
• New Life Spectrum, Algaemax: Not to be confused with others of the same name so check the ingredients. Does contain a lot of algal ingredients but I can’t comment further due to UK availability.
• C.E Essentials, Naturekind: While aimed at discus, Symphysodon it does contain a lot more algaes then other diets.
• Should you make your own? You can but and that is a big but narrowing down the gelling agent that can last a few hours. This is difficult and takes time. Making your own diet commands research into nutrition and I’m really just only a beginner I think in that. It’s a large initial financial input as the ingredients particularly algaes are not cheap. This might be the only solution for some people in many countries and it is a debate for me how to help there.

What genera are included in this (off the top of my head)?

• Acanthicus (maybe, the rest of that group isn’t)
• Acestridium
• Ancistrus
• Aphanotorulus
• Baryancistrus
• Chaetostoma
• Cordylancistrus
• Guyanancistrus
• Hemiancistrus
• Hypancistrus
• Hypoptopoma
• Hypostomus
• Isorineloricaria
• Lasiancistrus
• Nannoptopoma
• Otocinclus
• Panaqolus
• Panaque – Largely specialist for extracting microbes and fungi from wood.
• Parancistrus
• Parotocinclus
• Peckoltia
• Pogonopoma
• Pseudancistrus
• Pseudorinelepis
• Pterygoplichthys
• Rhinotocinclus
• Rinelepis
• Spectracanthicus – maybe excluding S. murinus
• Sturisoma
• Sturisomatichthys

Obviously I might forget a few or they aren’t even seen in the trade. There is also a lot we haven’t found on these fishes diets yet. I also haven’t included some that I put other niches for other reasons e.g. the substrate dwellers. I also can’t use common names as I’d end up making a list of hundreds for every common name there is.

Quick comment on wood ‘eaters’

These fishes have been proven as the article linked here cites to not digest wood or use it for digestion. Instead these genera Panaque, Panaqolus, the Hypostomus cochliodon group and Lasiancistrus heteracanthicus digest the microbes within wood in the wild but are just finding it in a different place. They do though consume and digest fungi. If wood within the aquarium had this diversity of microbes it’d decay very rapidly in captivity and it clearly doesn’t given a bit of wood can last years or over a decade.

So lets discuss supplements and additions to further cater for these fishes diets.

• Vegetables: The most well known and there are always long lists of what they can be fed. They should never replace the algaes as nutritionally do not even compare as even suggested in Trevi et al. (2023). There is always a use in having something when a fish is skinny or newly imported and just feeding, I particularly find sweet potato and courgette great there but it shouldn’t be relied on. For larger species additionally as just padding out their diet and adding to. Given these fishes are rarely if ever feeding on plants in the wild then there is a lot of nutrition that is not easily accessible from plants.
• Mushrooms: Now I separate these as the only fungi available to use aquarists, for those wood ‘eaters’; Panaque, Panaqolus, Hypostomus cochliodon group and Lasiancistrus heteracanthicus they can be of massive use given they feed on fungi in the wild. Potentially other algivores/detritivores might additionally feed on these but it is difficult to identify for many scientists if they do. I definitely recommend removing before 12 hours as it smells strong after being in an aquarium.
• Additional algaes: Algae powders can be brought and can be mixed in with diets like Repashy soilent green or super green to bulk them up. Just bare in mind they might expire quicker then the Repashy and the amount of gelling agent might not be sufficient for it to hold well with other ingredients. I wouldn’t recommend adding much and any dried seaweeds would need to be blended.
• Nori: All I can say is great if they will eat it but I think how easily it breaks down in the water column. So for some genera like Pterygoplichthys who are reasonably fast to feed it might actually work.
• Seeds: These feature reasonably in Hypancistrus diets but given monocots and dicots covers most plants it could mean a lot (Armbruster et al., 2007). I think there is no harm in trying seeds such as sunflower seeds but also small low acidic fruits such as blueberries or blackberries. It could be that these fishes are actually consuming fruits. I have seen multiple examples where Loricariids do feed on these small fruits not just Hypancistrus but Panaqolus seems keen on these food items. I’d definitely not look to citrus fruits, large amounts of fruit and apple seeds are best avoided.
• Growing rocks in the sun for algae: This can really work and is great for Otocinclus, it’s just being able to do so and the surface growing enough.
• Botanicals: These could provide benefits but in large amounts or certain types add a lot of complexity to an aquarium. I find additionally the biofilms botanicals produce actually vary in how they appeal to different fishes. They definitely wont sustain anything other then maybe a few of the smallest fish.
• Nettles: Potentially a great resource that needs to be explored more. Definitely dry than blanch for a few minutes in hot water for a few minutes to remove the sting.
• General fish foods: These typical diets might not always be bad if bulking out a diet particularly during periods where a fish needs more food.

Gut Biota, what and why?

This is an emerging science regarding to biology but has barely touched the ornamental fish industry beyond probiotics should they work. There is a lot to unpack and I think there is a benefit in having other fishes and their waste providing gut biota. These gut biota might have been lost during importing or a period of stress and poor diet. As much as gut biota might change with introduction after stressful periods diet does also influence this.

Wood

I generally in my day job look at Loricariid diets in the literature and other then the previously mentioned genera have never seen wood in the guts of other species. It is not needed and even those species who consume wood as a byproduct do not use it for digestion (Lujan et al., 2011) so is not needed in a diet. Even more so cellulose and lignin were proven not to be digested or used in digestion and these are added into many diets, so these are more wasted space and added waste to any fishes diet.

At the end of the day these are massively misunderstood fishes as is their diet. There are many more Loricariids to understand here such as the carnivores and substrate feeders.

References:

Alagawany, M., Taha, A. E., Noreldin, A., El-Tarabily, K. A., & Abd El-Hack, M. E. (2021). Nutritional applications of species of Spirulina and Chlorella in farmed fish: A review. Aquaculture, 542, 736841.

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

Chen, F., Qian, J., He, Y., Leng, Y., & Zhou, W. (2022). Could Chlorella pyrenoidosa be exploited as an alternative nutrition source in aquaculture feed? A study on the nutritional values and anti-nutritional factors. Frontiers in Nutrition, 9, 1069760.

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), 1-13.

Mazzoni, R., Rezende, C. F., & Manna, L. R. (2010). Feeding ecology of Hypostomus punctatus Valenciennes, 1840 (Osteichthyes, Loricariidae) in a costal stream from Southeast Brazil. Brazilian Journal of Biology, 70, 569-574.

Nonogaki, H., Nelson, J. A., & Patterson, W. P. (2007). Dietary histories of herbivorous loricariid catfishes: Evidence from δ 13 C values of otoliths. Environmental Biology of Fishes, 78, 13-21.

Valencia, C. R., & Zamudio, H. (2007). Dieta y reproducción de Lasiancistrus caucanus (Pisces: Loricariidae) en la cuenca del río La Vieja, Alto Cauca, Colombia. Revista del Museo Argentino de Ciencias Naturales nueva serie, 9(2), 95-101.

Van der Laan, R. & Fricke, R. (2023).  ESCHMEYER’S CATALOG OF FISHES: FAMILY-GROUP NAMES. (http://www.calacademy.org/scientists/catalog-of-fishes-family-group-names/). Electronic version accessed 04 October 2023.

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.

Trevi, S., Uren Webster, T., Consuegra, S., & Garcia de Leaniz, C. (2023). Benefits of the microalgae Spirulina and Schizochytrium in fish nutrition: a meta-analysis. Scientific Reports, 13(1), 2208.