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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).

Chaetostoma cf. joropo

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.

Chaetostoma sp. ‘L445/L457’

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.

Chaetostoma sp. ‘L445/L457’

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).

Figure 3: Hypancistrus sp. ‘L236’

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).

Apistogramma macmasteri, female

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

Male 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.

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.

Hybridisation, is it such a bad thing?

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Stendker blue turquoise discus, Symphysodon sp. x. at Maidenhead Aquatics, Ascot 2019.

Hybridisation is such a trigger word these days with many opinions for and against. First there are two definitions required:

Hybridisation: Interbreeding between two members of different species (Adah et al., 2013).

Crossbreeding: Interbreeding between two members of the same species, they might be the same variety/breed/cultivar or different.

These two terms are often used interchangeably even if they do not refer to the same event. Although these terms are different they do rely on the definition of species, genera and higher taxa which is hotly debated. One frequent definition being the biological species definition which relies on hybridisation being a barrier although is largely unreliable (Mallet, 2001).

Hybridisation as an event is not uncommon (Scribner et al., 2000), the event (or events) has resulted in the development of new species, a process known as speciation (Litsios & Salamin, 2014). Not all of the offspring might be fertile, many people in the aquarium trade might be familiar with the hybrid parrot cichlids (Amphilophus citrinellus x. Heros efasciatus), this may be the biggest barrier to speciation.

Synodontis sp. at Maidenhead Aquatics, Ascot 2019.

Barriers to Hybridisation

There are many barriers to hybridisation which really can effect the result if there is some compatibility.

Chromosomal number is the most well known barrier to hybridisation, chromosomes are units within the nucleus that contains all the DNA. Most humans have 22 pairs, fruit flies, Drosophila melanogaster have 4 pairs and the duckbilled platyplus has 26 (a lot of sex chromosomes though!), chromosomal number does not infer complexity at all and nor does the size of a genome. Generally different species might have a different number of chromosomes, this is very well displayed in the Loricariid (pleco) genus, Ancistrus (bristlenoses) which displays a diversity of different chromosomal numbers across a 50 or more species large grouping (Santos da Silva et al., 2022). During reproduction parental chromosome numbers ideally need to match to put simply. While this is a barrier it has resulted in infertile offspring, or in the example of the livebearers from Poecilidae a number of unusual adaptations. These hybrid Poecilidae have the ability to reproduce via gynogensis, asexual reproduction with the requirement of a male to stimulate the process, he contributes nothing to the offspring (Schultz, 1969) and this is displayed potentially in many species originating from hybridisation (Turner, 1980). The limitations of chromosomes really vary though but are definitely present.

Morphology is one of the obvious but so easily forgotten, organisms have to be morphologically compatible not just for the initial act but additionally for fertilisation and gestation. It might not seem it but that minor differences in morphology make a difference, what might seem obscure such as the shape of spermatozoa can differ resulting in the cell not being able to imbed into the egg, it’s even so diverse that the morphology of this cell can infer groups (Quagio-Grassiotto et al., 2020). Species often judge each other via their morphology and therefore there is some level of sameness particularly in the wild.

Behaviour, different species or even different populations might display very different behaviours. Behaviour itself is so integral to reproduction and mate choice, outside of captivity this is such a strong barrier.

Geography is maybe the most well known barrier and often can result in the other divisions. This can be within a small space such as fishes which inhabit deeper water whereas others the shallows. Barriers don’t always have to be spatial but they can also be temporal.

Golden dwarf cockatoo cichlid, Apistogramma cacatuoides

The issues with hybridisation

Hybridisation itself is not negative it’s just a force, in terms of conservation it can provide a variety of effects. Hybridisation can lead to the decline in a population of a species, most well known in the case of the Scottish wildcat (Felis silvestris silvestris) and the sister species, the domestic cat (Felis catus). As hybrids display what is known as a hybrid vigour (a mixture of traits between the two pariental species) it can change how these individuals interact with their environment and the genetic diversity of a species (Selz & Seehausen, 2019). The ecological impact of the introduction of hybrids can be described as unpredictable (Mandeville et al., 2022) which makes it difficult to identify those exact issues. Although, this argument is similar to introducing individuals who are selectively bred who might also influence the gene pool of wild individuals. It is generally not ideal, hybridisation in conservation is reserved for restoring species where no other alternative can be found e.g. Prezewalski’s horse (Equus ferus prezewalskii) and the domestic horse (Equus ferus caballus) in an effort to save the subspecies, although hybridisation is a risk to the subspecies (King, 2005).

But here we are talking about captivity, it’s highly unlikely any of our fishes will be involved in any real conservation effort or practices.

The main issue in captivity with these hybrids is so many do not go recorded, likely due to misidentifications of the parent species and lack of record keeping. Take Ancistrus dolichopterus, this species is generally diagnosed as having 8-9 soft dorsal rays, only one small individual was spotted excluding brown spots on the abdomen. While no seams were mentioned (Kner, 1854) it is commonly stated they display these, as with many other Ancistrus these often do fade with time and I have been shown individuals from the type locality lacking these seams. There are many spotted Ancistrus and over time localities and important information on them are lost. It’s more then often that these seams are how the judgement is based on what species it is. The point I am getting to is how well do we know these species and how they are defined? We are relying here on hybridisation not being able to occur but it likely does because species are kept together who are not the same species but assumed the same. I generally would assume unless wild caught for morphologically indistinctive Ancistrus, they should probably be assumed hybrids. I have frequently seen even Ancistrus ranunculus, a morphologically distinctive Ancistrus be misidentified so it’s a difficult situation. This doesn’t include how little we know about some genera, the frequency of bycatch and misidentifications from suppliers as well.

Surely those who argue against hybridisation should also argue against crossing those from different localities or populations. This is also changing the genetic landscape of a population and asks the question of how to define a species.

In captivity it does effect if you are getting what you think you are getting but for many this might not be an issue. One of the biggest worries though is because hybrids are a pick and mix of the parental species morphology and behaviour is largely unknown, it could be more similar to one parent then the other, an intermediate or totally different. Where parental species have different requirements this is also an issue.

Platy, Xiphophorus sp. x. unknown likely X. maculatus x. X. variatus.

How to avoid hybridisation

For wild caught fishes maybe getting fishes from the same source and checking locality matches if you are not completely confident on the identification. Keep records of who is being crossed with who.

It’s quite simple to keep those who could maybe hybridised apart, this is difficult to judge as it is not just about genera but if it looks similar don’t keep them together. If hybridisation occurs clearly record that and any offspring should be sold labelled as such, if possible to pet only homes with no worries of breeding where that label can be forgotten over generations.

For captive bred individuals the situation is difficult, if you aren’t sure and they aren’t from a responsible or reliable source then don’t buy unless you plan on just having the animals as a pet, assuming you don’t want to increase the number of hybrids.

Hybridisation Bias

The skull of the parrot cichlid, Amphilophus sp. x. Vieja sp. as posted by Fish_Man_Dan on Monster Fish Keepers forum: https://www.monsterfishkeepers.com/forums/threads/my-mind-is-made-up-about-the-creation-of-blood-parrots.374666/

Much of the dislike towards hybrids is focused on certain species although hybrids are much more common then they seem. Fishes such as domestic discus (Symphysodon spp.) are a mixture of the three different species and definitely the different localities depending on the variety (Ng et al., 2021). Some domestic species might have hybrid origins such as the common bristlenose, Ancistrus sp. but we do not know. These species do not seem to have health related defects from their morphology although those such as the parrot cichlid, Amphilophus sp. x. Vieja sp. (not to be confused with the true parrot cichlid, Hoplarchus psittacus), clearly does have health related deformities as a result of selective breeding and hybridisation as displayed in this link to a Monster FishKeepers discussion forum.

The true parrot cichlid, Hoplarchus psittacus at Pier Aquatics, 2021

Conclusion

Hybridisation will always occur in the hobby, it is best that it is labelled so future keepers are aware of what their fishes are. If you are not completely sure of the species you are keeping then don’t breed it, ideally anyone who can identify the species should be able to cite a reliable website or the description of the species. Undescribed species might not have this so should have more precautions made such as keeping to one locality and morphology.

References

Adah, P. M., Onyia, L. U., & Obande, R. A. (2013). Fish hybridization in some catfishes: A review.

King, S. R. (2005). Extinct in the Wild to Endangered: the history of Przewalski’s horse (Equus ferus przewalskii) and its future conservation. Mongolian Journal of Biological Sciences, 3(2), 37-41.

Kner, R. (1854). Die Hypostomiden: Zweite Hauptgruppe der Familie der Panzerfische.(Loricata vel Goniodontes) (Vol. 1). KK Hof-und Staatsdruckerei.

Litsios, G., & Salamin, N. (2014). Hybridisation and diversification in the adaptive radiation of clownfishes. BMC Evolutionary Biology, 14, 1-9.

Mallet, J. (2001). Species, concepts of. Encyclopedia of biodiversity, 5, 427-440.

Mandeville, E. G., Hall Jr, R. O., & Buerkle, C. A. (2022). Ecological outcomes of hybridization vary extensively in Catostomus fishes. Evolution, 76(11), 2697-2711.

Ng, T. T., Sung, Y. Y., Danish-Daniel, M., Sorgeloos, P., de Peer, Y. V., Wong, L. L., & Tan, M. P. (2021). Genetic variation of domesticated discus (Symphysodon spp.). Aquaculture, Aquarium, Conservation & Legislation, 14(2), 832-840.

Schultz, R. J. (1969). Hybridization, unisexuality, and polyploidy in the teleost Poeciliopsis (Poeciliidae) and other vertebrates. The American Naturalist, 103(934), 605-619.

Santos da Silva, K., Glugoski, L., Vicari, M. R., de Souza, A. C. P., Noronha, R. C. R., Pieczarka, J. C., & Nagamachi, C. Y. (2022). Chromosomal Diversification in Ancistrus Species (Siluriformes: Loricariidae) Inferred From Repetitive Sequence Analysis. Frontiers in Genetics, 13, 838462.

Scribner, K. T., Page, K. S., & Bartron, M. L. (2000). Hybridization in freshwater fishes: a review of case studies and cytonuclear methods of biological inference. Reviews in Fish Biology and Fisheries, 10, 293-323.

Selz, O. M., & Seehausen, O. (2019). Interspecific hybridization can generate functional novelty in cichlid fish. Proceedings of the Royal Society B, 286(1913), 20191621.

Turner, B. J., Brett, B. L. H., & Miller, R. R. (1980). Interspecific hybridization and the evolutionary origin of a gynogenetic fish, Poecilia formosa. Evolution, 34(5), 917-922.

Quagio-Grassiotto, I., Baicere-Silva, C. M., de Oliveira Santana, J. C., & Mirande, J. M. (2020). Spermiogenesis and sperm ultrastructure as sources of phylogenetic characters. The example of characid fishes (Teleostei: Characiformes). Zoologischer Anzeiger, 289, 77-86.

A Fish to Do a Task: Algae Eating Fishes Within the Freshwater Aquarium

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When keeping an aquarium for the first time many are confronted with algaes, they cover the glass, plants, decor or even the water itself. Fishes that feed on algaes, known as algivores are often deployed here, sometimes mistakenly.

Pterygoplichthys joselimaianus (Common pleco, L001, gold spot pleco)

This I can only assume stems from the idea of a “clean up crew” and an aquarium ‘ecosystem’. The problem here is it is generalising algivores and misunderstanding this dietary niche in general because more then often we all keep algivores because they don’t fit the aesthetic we might not even know. Freshwater ecosystems are very complex and function cannot realistically be replicated in the aquarium.

Who are the algivores?

Algivores come from almost every branch of “fishes” from Cichlidae (Cichlids; Burress, 2016) to Siluriformes (catfishes). Even within these clades there is a wide amount of variation, in cichlids it’s quite obvious but in plecos, Loricariids there is a small number of carnivores and omnivores (Lujan et al., 2012). The actual mechanism of feeding varies a lot and this no doubt influences what algaes they can eat. Even within these groups there is a lot of variation in what algaes they will feed on (Delariva & Agostinho, 2001).

Both of these statements make sense when you buy algivores and they do not feed on some or all of the algaes that are causing an issue in the aquarium. Cyanobacteria makes the best example here, while many fishes do feed on it in the wild (Valencia & Zamudio; Baldo et al., 2019) it’s very evident they do not feed on the cyanobacteria that pests the aquarium, they are likely very different algaes. In many freshwater ecosystems there will be multiple species who feed on algaes and they could only co-exist if there was some partitioning in what algaes they feed on. Most of these fishes also feed on other microbes such as bacteria, protozoa etc. We even see divergent morphology likely based on what and the proportions of the different algaes and those other they feed on. This is where a common misconception comes, many will state that quite a lot of these fishes aren’t algivores because they aren’t ‘cleaning’ your aquarium.

So there is a lot of understanding the individual fishes to know what algaes they will eat and how much.

Another aspect here is the behaviour of algivores is often forgotten as they become more of a purpose then of a focus. Otocinclus, flying foxes (Epalzeorhynchos spp.) and Siamese algae eaters (Crossocheilus spp.) are shoaling and really do benefit from a minimum of 6 as shown here in the wild: https://www.inaturalist.org/taxa/98678-Crossocheilus-reticulatus/browse_photos. For Otocinclus they are shy when housed in small numbers, they are found in their hundreds in the wild. Epalzeorhynchos and Crossocheilus on the other hand in small numbers can become boisterous to each other and other fishes, there is no better example of this then E. bicolor. While for Otocinclus providing a group is rarely an issue for others it could be very limiting on aquarium size and particularly only to feed on one type of algae.

I can’t help but emphasize these fishes have their own requirements and they can be extremely specialized. Just because they feed on algae it does not mean they do not require a specialised environment based on their natural habitat. This is maybe why I see such a high mortality in certain species.

One thing never to forget is how long a fish might live and if it is only to solve an issue that might last a week or a few months you’ll have the fish years or even decades. Particularly catfishes, Loricariids/plecos, who are exceptionally long lived as often discussed in conversations:

Rehoming for some of these fishes can provide a particular challenge.

So what are the commonly recommended algivores:

Otocinclus sp.

Otocinclus spp.

Common name: Dwarf pleco, Oto

Locality: Widespread across South America (GBIF Backbone Taxonomy, 2023; Fricke et al., 2023)

Size: 16.5-43.8mm Standard Length (SL; Shaefer, 1997)

Comments: A small, shoaling (Axenrot & Kullander, 2003) genera found in clear, sandy waters with plenty of vegetation (Reis, 2004). This genus specialises in the finer algaes and other microbes growing on the variety of surfaces (Axenrot & Kullander, 2003). Otocinclus as a name has been used as a common name to refer to many other Hypoptopominae not all that stay that small, some such as Hypoptopoma incognitum at 9.4cm SL (Aquino & Schaefer, 2010). These other Hypoptopominae (The subfamily of Loricariidae that contains Otocinclus) are still just as social and some can be much more challenging to feed and sustain in captivity. I personally find particularly Rhinotocinclus and Nannoptopoma really suffer with the majority of ‘algae’ wafers where there isn’t a high amount of algae’s in the ingredient list. Otocinclus definitely do deal with the algae in an aquarium but not all such as black beard or cyanobacteria, after the algae is gone though they will need a more specialist algae based diet.

Common bristlenose, Ancistrus sp.

Ancistrus sp. ‘Common bristlenose’

Common name: BN, bristlenose pleco.

Locality: Unknown.

Size: 12-20cm SL, very variable.

Comments: This is a domestic species you’ll often see associated with Ancistrus cirrhosus or Ancistrus dolichopterus but it is related to neither of these species. As this species has been bred into many different variants from albino, super red, snow white to green dragon, there is additionally a lot of variation in size. It also makes any husbandry a lot more unpredictable as we neither know what the original species is nor can we really say how domestication has effected them. Unlike a few other Ancistrus this species is territorial and can take on any similarly shaped fishes if they enter their space, unlike many misconceptions this is regardless of sex. These do feed on algae but I can’t say they will deal with any on plants, nor black beard algae, cyanobacteria or most diatoms. Given how long these fishes can live and their size, certainly a consideration for any tank and they still have their own requirements.

Crossocheilus sp., photo taken by Chiroptera man This file is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license.

Epalzeorhynchos, Crossocheilus and Tariqilabeo 

Common name: Sharks, algae eaters and flying foxes.

Locality: East Asia.

Size: 12.46cm SL (Ciccotto et al., 2017) although individuals potentially grow up to 15cm SL in captivity.

Comments: As mentioned above generally social fishes who are boisterous with age in low numbers. They are brilliant in the right situation but temperatures definitely have to be considered for example the fishnet flying fox, Crossocheilus reticulatus who inhabits rapids and much cooler temperatures then generally expected. Certainly underrated fishes where they are almost never kept as the focus of an aquarium. Often noted to feed on black beard algaes but I’m not sure they are that rapid at it.

There are soo many fishes recommended and this changes with time such as the hillstream loaches, Gastromyzontidae who inhabit the rocky rapids of Asia but I might ask to look at these fishes in the wild and how specialised they are: https://uk.inaturalist.org/taxa/1032183-Gastromyzontidae/browse_photos

The actual problem, algaes

It is no doubt true that algaes can release toxins, these algaes have not been seen in the freshwater aquarium. Therefore, there is no real harm to algaes themselves excluding blocking filter inlets, outlets and sponges. More then anything algaes are a symptom of a variety of nutrients or conditions, some of them just might be an aquarium stabilising over the years.

Aquariums do have an ecosystem when it comes to microbes and with time the composition of these microbes will change. Aquariums don’t seem to really stabilise for years, obviously this likely wont have any scientific research behind it but if we look at natural ecosystems succession is a well known process. Succession is where the organisms change over time, while species diversity increases over time towards the end it then decreases. There is no same end goal to succession as it varies on so many factors and succession can be halted by certain species or environmental factors.

Of course the best method in the short term is likely really manually removing algae, this will likely effect this succession as removing the microbial populations that are competing with the algaes. Having worked in stores I use a variety of tools (ensure they are used for nothing else):

  • Scouring pad: Be careful on acrylic but this is great for most algaes and with a bit of hard work even diatoms.
  • Toothbrush: This is for the corners but can even work on decor. It can make a good attempt on blackbeard algae. Do not use too harshly on the corners as can damage and remove silicone.
  • Stanley blade: Definitely very sharp so be careful! Used wrong it can scratch glass and acrylic. Once you work out the right angle it’s great for removing any algaes such as diatoms and blackbeard on flat surfaces.
  • Filter Floss: Sometimes can be useful to clean large areas of soft algae, it can scratch the glass if catches sand granules but an easy thing to grab.

I personally do not recommend any of the magnetic algae cleaners due to the fact they tend to only remove the softest algaes and can easily catch sand, scratching the glass. T

Algaes themselves would deserve their own article but because of the polyphyletic (pick and mix) nature of the term between many very diverse groups of organisms, just because they are photosynthetic they aren’t simple.

I would treat algaes for mature aquariums particularly any sudden change in algaes present as biological indicators of nutrients, often ones we can’t or rarely test for.

The relationship between nutrients and algaes

Algal growth is inherently connected to nutrient composition. Unlike plants algaes can reproduce at a much more rapid rate taking advantage of any nutrients, the amount of algaes is usually connected to higher nitrate (Taziki et al., 2015) and phosphate levels (Fried et al., 2003). This makes sense as while a lot of rivers contain algaes which can contribute to the majority of the trophic interactions from photosynthesis, naturally rivers and lakes are oligotrophic (Lewis et al., 2001). Some of this nutrients we can’t help like nitrates out of the tap but when simply water changes which will benefit the health of the fish, what is the harm of that 30-60 minutes a week? Surely even a hamster, snake etc. takes more time. In another article I will probably discuss how to deal with when the source water is causing issues other then my article on RO.

Some sources of nutrients are easily forgotten, from certain botanicals to certain substrates. If it is the substrate usually it’ll be there from the beginning but adding certain botanicals like palms it’ll appear later on.

Conclusion

Algaes themselves are harmless and I think at some point we need to see them for what they are, maybe more interesting indicators.

References:

Aquino, A. E., & Schaefer, S. A. (2010). Systematics of the genus Hypoptopoma Günther, 1868 (Siluriformes, Loricariidae). Bulletin of the American Museum of Natural History, 2010(336), 1-110.

Axenrot, T. E., & Kullander, S. O. (2003). Corydoras diphyes (Siluriformes: Callichthyidae) and Otocinclus mimulus (Siluriformes: Loricariidae), two new species of catfishes from Paraguay, a case of mimetic association. Ichthyological Exploration of Freshwaters, 14(3), 249-272.

Baldo, L., Riera, J. L., Salzburger, W., & Barluenga, M. (2019). Phylogeography and ecological niche shape the cichlid fish gut microbiota in Central American and African Lakes. Frontiers in microbiology, 10, 2372.

Burress, E. D. (2016). Ecological diversification associated with the pharyngeal jaw diversity of Neotropical cichlid fishes. Journal of Animal Ecology, 85(1), 302-313.

Ciccotto, P. J., Pfeiffer, J. M., & Page, L. M. (2017). Revision of the cyprinid genus Crossocheilus (Tribe Labeonini) with description of a new species. Copeia, 105(2), 269-292.

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

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

Fried, S., Mackie, B., & Nothwehr, E. (2003). Nitrate and phosphate levels positively affect the growth of algae species found in Perry Pond. Tillers, 4, 21-24.

Lewis Jr, W. M., Hamilton, S. K., Rodríguez, M. A., Saunders III, J. F., & Lasi, M. A. (2001). Foodweb analysis of the Orinoco floodplain based on production estimates and stable isotope data. Journal of the North American Benthological Society, 20(2), 241-254.

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.

Otocinclus Cope, 1871 in GBIF Secretariat. GBIF Backbone Taxonomy. Checklist dataset https://doi.org/10.15468/39omei accessed via GBIF.org on 2023-10-24.

Reis, R. E. (2004). Otocinclus cocama, a new uniquely colored loricariid catfish from Peru (Teleostei: Siluriformes), with comments on the impact of taxonomic revisions to the discovery of new taxa. Neotropical Ichthyology, 2, 109-115.

Schaefer, S. A. (1997). The Neotropical cascudinhos: systematics and biogeography of the Otocinclus catfishes (Siluriformes: Loricariidae). Proceedings of the Academy of Natural Sciences of Philadelphia, 148, 1-120.

Taziki, M., Ahmadzadeh, H., Murry, M. A., & Lyon, S. R. (2015). Nitrate and nitrite removal from wastewater using algae. Current Biotechnology, 4(4), 426-440.

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.

What is a pleco? To be a pleco or not to be a pleco

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Common names are half a mystery to themselves, their origins and what species they really apply to and not. They lack regulations and frequently change spatially and temporally. You can’t expect to go to every country and people call a giraffe, Giraffa, a giraffe. It’s like you can’t expect common names to stay the same, a well known example would be the European robin, Erithacus rubecula was at one point called the redbreast and then that changed to robin redbreast and then just robin. The point maybe is common names change so much with little ability to track, plant common names do so frequently as well.

Pleco is one of those common names, originally Plecostomus but Plecostomus used to be the name of a genus. Much like many have created Cory as a common name for the genus Corydoras. The type and most notable species was Hypostomus Plecostomus (Linnaeus 1758), formally Plecostomus Plecostomus. Plecostomus is no longer a valid genus and has not been since 1980 where species were then placed in multiple other genera such as Ancistrus, Isorineloricaria, Loricariichthys and eventually Aphanotorulus. The majority of those previously known as Plecostomus were moved into Hypostomus, described in 1803 with the type Hypostomus guacari which is now understood to be a synonym of Hypostomus plecostomus (Fricke et al., 2023). Interestingly Pterygoplichthys, a genus that contains species known as the common plecos was never in the genus Plecostomus. This summarizing the main flaws of the arguments behind the common name. Ancistrus, bristlenose plecos are often argued not to be plecos but they had members once in Plecostomus whereas many such as Pterygoplichthys who there is no debate about were never placed in Plecostomus. Currently while there are none with the genus Plecostomus there is Hypostomus plecostomus and H. plecostomoides. Of genera Neoplecostomus, Microplecostomus and Nannoplecostomus exists, currently within Hypoptopominae, which is the same subfamily as Otocinclus. These genera add the other argument do people consider Otocinclus a pleco?

The other issue with the name pleco as a common name is where it is applied evolutionary.

Phylogenetic tree using molecular data of Loricariidae from: Roxo, F. F., Ochoa, L. E., Sabaj, M. H., Lujan, N. K., Covain, R., Silva, G. S., … & Oliveira, C. (2019). Phylogenomic reappraisal of the Neotropical catfish family Loricariidae (Teleostei: Siluriformes) using ultraconserved elements. Molecular phylogenetics and evolution, 135, 148-165.

Names need some consistency so people can understand each other and that is what scientific names provide. The common name pleco also lacks consistency in where it places in the evolutionary/phylogenetic tree. If you exclude Ancistrus as so many do it is the only member of Hypostominae (coloured in red, Fig 1) to not be a pleco. But members outside of that subfamily are included, right at the earliest branches is Rinelepinae (coloured in yellow, Fig 1) it excludes a lot of later branching Loricariids. Not pictured here is also Pseudancistrus geniseiger who would be considered a pleco and also branches out this far (Lujan et al., 2015). Loricariinae and Hypoptopominae are often debated as if they are a pleco or not.

The problem is more that no one is quite referring to pleco in the same way under this pick and mix system. Some of us refer to the whole of Loricariidae as it would make sense to do, L numbers themselves also do as the L refers to Loricariidae. In Germany these fishes are often referred to as L Welse, meaning Loricariidae Catfish I assume as also members of Siluriforme, catfishes. It means everyone understands each other using this method even if being much broader, we should be recognising the diversity within Loricariidae anyway. In Loricariids and therefore plecos it is an international aspect of the fishkeeping hobby and many countries do not even use the term pleco.

References:

Britto, M. R. (2003). Phylogeny of the subfamily Corydoradinae Hoedeman, 1952 (Siluriformes: Callichthyidae), with a definition of its genera. Proceedings of the Academy of Natural Sciences of Philadelphia, 153(1), 119-154.

Fricke, R., Eschmeyer, W. N. & Van der Laan, R. (2023).  ESCHMEYER’S CATALOG OF FISHES: GENERA, SPECIES, REFERENCES. (http://researcharchive.calacademy.org/research/ichthyology/catalog/fishcatmain.asp). Electronic version accessed 18/10/2023.

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.

Roxo, F. F., Ochoa, L. E., Sabaj, M. H., Lujan, N. K., Covain, R., Silva, G. S., … & Oliveira, C. (2019). Phylogenomic reappraisal of the Neotropical catfish family Loricariidae (Teleostei: Siluriformes) using ultraconserved elements. Molecular phylogenetics and evolution, 135, 148-165.

The Medusa Pleco’s, Ancistrus spp. which do you have if one at all?

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Ancistrus commonly known as bristlenose plecos, is a gigantic genus with around 50 spp. currently described but many more undescribed species. They are generally described with the presence of tentacles on the head unlike other Loricariids with the exception of Lasiancistrus tentaculatulatus. Tentacles are not a defining feature though for Ancistrus, there are many species who lack them and previously might have been known under the genera Xenocara.

A common misconception is the connection between tentacles and the sex of the fish which is maybe a half truth as for quite a few females tend to have small to no tentacles whereas males develop substantial (hypertrophied) tentacles. Of course there are exceptions here so lets discuss the mythical medusa plecos.

So who are the species called the medusa plecos:

Ancistrus ranunculus Muller et al., (1994)

Common name: L034

Location: Rio Xingu, Brazil

Diagnosis: This is one of the most extreme Ancistrus. This species displays a wide, flat, triangular head. The name ‘ranunculus refers to tadpole and this species definitely looks like the flattest and widest of tadpoles. Some what variable in body shape.

Males and females display very impressive tentacles, males do display often a double row of these tenatacles who are slightly larger. Either way females are often confused with being male.

Colouring is solid black with maybe a little of a blue tinge but not much. When stressed they often express white patches. Juveniles can be spotted in some variants they can have very small almost invisible spotting to maturity.

Ancistrus sp.

Common name: L255, spotted medusa pleco.

Location: Rio Xingu, Brazil

Length: 15cm SL

Diagnosis: This is very very similar to Ancistrus ranunculus although displays spotting into maturity which doesn’t disappear when relaxed. They are very striking and could be confused if it was not for that flat, triangular body shape with A. dolichopterus and other spotted Ancistrus.

Debatable if a new species or not.

Ancistrus macropthalamus Pellegrin (1912)

Common name: LDA074, blue medusa pleco.

Location: Rio Orinoco, Columbia

Length: 7-10cm SL.

Diagnosis: Flat with larger but rounder head then Ancistrus ranunculus. It is very unusual in comparison regarding eye placement to many Ancistrus.

Colouration is much more with a blue tinge and can be spotted but usually not into maturity.

Tentacles tend to be equal size between both sexes.

Ancistrus aguaboensis Fisch-Muller et al. (2001)

Common name: L032, green medusa pleco.

Length: 5cm SL.

Location: Rio Tocatins, Brazil.

Diagnosis: Almost much more like the traditional small Wild Ancistrus. It is some what of a flat head but not particularly wide.

Colouration is a brown/green tone with white spots, nothing impressive.

Tentacles are very sexually dimorphic and while females have tentacles are much smaller.

The Locality Clue

I have to empathise how important the difference in locality is. Always ask where these fishes were imported from as they will not be imported from other countries then their locality listed here. Ancistrus ranunculus is a Brazilian species and this is the biggest mistake as people will sell the Columbian Ancistrus macropthalamus under this name and label.

Husbandry

Not the focus of this article but half a warning. The morphology of these Ancistrus is based on high velocity of water not just that but high temperatures, 28c or more. I’ve tried lower at 26c and it was an awful failure, I don’t just say this from my experience. The Rio Xingu for Ancistrus ranunculus and Ancistrus sp. ‘L255’ rarely if ever dips below 28c (Rofrigues-Filho et al., 2015). Even below they struggle to feed. The other aspect is that as temperature increases oxygen saturation decreases and these are high velocity fishes so a good current is important either a powerhead, wavemaker or a strong air pump.

Many of these Ancistrus are gregarious, social but none more so then the Ancistrus ranunculus and Ancistrus sp. ‘L255’. It came to my notice when I saw so many people struggling but everyone with success had theirs as a group. Even in the ecological and species description of Ancistrus raununculus notes them as gregarious listed as unlike Hypancistrus zebra (Muller et al., 1994). These fishes generally are social in their own space but it goes elsewhere to where they might struggle to feed otherwise.

Diet might be one of the most important aspects of many fishes husbandry, it also is maybe the most forgotten. Most Ancistrus lack any dietary information although Ancistrus ranunculus has some records suggesting they are almost entirely algivores (Zuanon, 2019). Maybe there is evidence to suggest much more diversity to the genus. Generally this genus is very specialist and I cannot empathise the importance of Repashy soilent green.

Ancistrus is one of the most misunderstood genera maybe because everyone sees the common bristlenose, Ancistrus sp. who is largely much more hardy. There are slow feeding species who don’t compete well but could be much more successful in captivity if not treated like side on. They definitely require a tank being considered around them and while I’d love to see more species in the hobby I’d love there be more demand for treating this genus as it is, a pain!

References:

Fisch-Muller, S., Mazzoni, R. & Weber C. (2001). Genetic and morphological evidences for two new sibling species of Ancistrus (Siluriformes: Loricariidae) in upper rio Tocantins drainage, Brazil. Ichthyological Exploration of Freshwaters. 2(4): 289-304.

Muller, S., Rapp Py-Daniel, L. H. and Zuanon, J. (1994). Ancistrus ranunculus, a new species of loricariid fish (Siluriformes: Loricariidae) from the Xingú and Tocantins rivers, Brazil. Ichthyological Exploration of Freshwaters. 5 (4): 289-296.

Pellegrin, J. (1912). Description d’un poisson nouveau de l’Orénoque appartenant au genre Xenocara. Bulletin de la Société Zoologique de France. 37:271-272.

Rodrigues-Filho, J. L., Abe, D. S., Gatti-Junior, P., Medeiros, G. R., Degani, R. M., Blanco, F. P., Faria, C. R. L., Campanelli, L., Soares, F. S., Sidagis-Galli, C. V., Teixeira-Silva, V., Tundisi, J. E. M., Matsmura-Tundisi, T. and Tundisi, J. G. (2015). Spatial patterns of water quality in Xingu River Basin (Amazonia) prior to the Belo Monte dam impoundment. Brazilian Journal of Biology, 75(3).

Zuanon, J. A. S. (1999). “História natural da ictiofauna de corredeiras do rio Xingu, na região de Altamira, Pará” Unpublished Thesis. Dept. Ecologia Universidade Estadual de Campinas : Campinas, SP

You are what you eat – Livefood edition.

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So often we don’t really think about what we are feeding our fishes but when we do, do we consider what the food is being fed? This isn’t much of a consideration when it comes to prepared feeds because the companies and manufactures will cater for that. Regarding live foods then what they are fed is up to you. Nutrition doesn’t come out of thin air and unlike plants they cannot manufacture a lot of the sugars.

Here I think we can exclude anything that is not carnivorous as their food requires very different nutrition or more correct fertilising which is a whole other topic.

The term relevant here is known as gut loading and largely refers to the feeding of invertebrate prey to increase nutrition.

Why gut load prey?

As previously mentioned gut loading increases the nutritional value of the prey provided, when initially bought from the store the food item might be low in nutrition particularly calcium and many vitamins (Boykin et al., 2021). While calcium is taken up from the environment in fishes there is still a dietary requirement which varies depending on the species and the environmental calcium values (Baldisserotto et al., 2019) explained a little bit more in my article on mineral content and fish biology.

Considerations

Just feeding anything to the invertebrate feeders wont provide the nutrition required. Whatever going into the prey should be going into the fish so it needs to be a complete diet and there is no benefit from reduced quality. The easiest way to do this would be feeding a complete fish food whether it be dry or a gel diet, alternatively there are many products based on gut loading insects. The issue with exact nutrients required for using feeders depends on the prey item (Finke et al., 2003) and the fish you are feeding of which most will not have complete nutritional studies (Teles et al., 2022; Velasco-Santamaría & Corredor-Santamaría, 2011).

Channa aurantimaculata, the cobra snakehead.

Time after gut loading is also important likely due to that nutrition being used for metabolism and other physiological processes, for dubia roaches and snails after around 1 hour calories decreased but fat content did continue increase up to 12 hours. Mealworms on the other hand nutrition only increases till the 6 hour mark where that creased (Gorst et al., 2015).

What should I gut load?

This really depends on the food items you are using as stated before and what it is possible to feed them. Excluding earthworms fish food would be a logical choice for most, I would not actually say it’d be a bad idea to use generic fish foods to at least meet all of those basic nutritional requirements. Generally a great rule for vegetables in addition to these fish foods is anything but the onion/garlic family so unlike herbivorous rodents even mushrooms. For snails definitely supplement the calcium with cuttlefish shells.

Bran is popular for feeding many feeders particularly insects, it’s not entirely clear the nutritional value of bran as a diet and at least compared to carrots it does seem to have benefits that carrots don’t have and vice versa (Fasce et al., 2022). I wouldn’t be opposed to it’s use with other items included in the insects diet.

Now there are things I would definitely consider avoiding, iceburg lettuce due to low nutrient value and for providing moisture there are many other alternatives.

A. fulica, African land snails. One of the smaller but most common species under that common name.

For feeding snails there are many resources on how to feed them, many snail specialist diets even if maybe not needed around. I give my land snails, A. fulica a variety of vegetables along with frequent fish food that has been mixed in with warm water, not that I use them to feed fishes. Herbs can be really great to add to this mixture of fish food. The fish food is to provide protein as definitely these snails are detritivores, omnivores who can be fed pinkie mice, mealworms and I’ve fed mine dubia roaches obviously those who are not alive though!

This does seem a very understudied topic when it comes to fishes and maybe because when it comes to food that needs to be gut loaded it is largely in the realm of ornamental fishes. I personally think citizen science could easily provide some answers such as whether fish condition improves depending on what the feeder is fed, the issue with calcium might be harder to answer though.

The Ethics

This is the final maybe most important statement. Live feeding obviously comes with ethics. In the UK invertebrates are not included under the Animal Welfare Act 2006 and are therefore not protected by law in terms of their welfare, this is largely why I do not mention fishes here. Fishes as a vertebrate are included in the Animal Welfare Act 2006, section 4 clearly stating they are protected from unnecessary harm. There are no fishes in wide distribution or distribution at all in the UK which are obligatory piscivores requiring a live feeder. Live feeding using vertebrates carries a higher parasite and even damage risk to the fish. Many of these fishes are not piscivores or would feed on vertebrates in the wild.

That is the legislation, the personal ethics and sentience of invertebrates is a long debate. I personally believe all animals should be treated with respect so when feeding invertebrates they shouldn’t be exposed to any suffering where possible. Certain Crustaceans and Cephalopods are protected by law in the UK, particularly the octopus and decapods under the Animal Welfare (Sentience) Act, 2022. It doesn’t seem clear to what extent these animals are protected. This legislation was introduced to recognise the intelligence of such animals. So the live feeding of these should be avoided.

The use of unprotected invertebrates in live feeding is not always a necessity and that should be recognised. This method of feeding is a lot more challenging to meet a fishes nutritional needs so if possible I’d recommend against. Of course some fishes need help after acclimating from the wild or even import. Some species are of particular challenges due to their specialised feeding morphology and behaviour. I would argue if creative enough most fishes can be pushed onto frozen, gel or dry, if not should we question their place in the hobby like many Gymnotiformes and Mormyrids? Or even leave them with those who can cater for them.

References:

Baldisserotto, B., Urbinati, E. C., & Cyrino, J. E. P. (Eds.). (2019). Biology and physiology of freshwater neotropical fish. Academic Press.

Boykin, K., Bitter, A., & Mitchell, M. A. (2021). Using a Commercial Gut Loading Diet to Create a Positive Calcium to Phosphorus Ratio in Mealworms (Tenebrio molitor). Journal of Herpetological Medicine and Surgery, 31(4), 302-306.

Fasce, B., Ródenas, L., López, M. C., Moya, V. J., Pascual, J. J., & Cambra-López, M. (2022). Nutritive value of wheat bran diets supplemented with fresh carrots and wet brewers’ grains in yellow mealworm. Journal of Insect Science, 22(3), 7.

Finke, M. D. (2003). Gut loading to enhance the nutrient content of insects as food for reptiles: a mathematical approach. Zoo Biology: Published in affiliation with the American Zoo and Aquarium Association, 22(2), 147-162.

Gorst, V. M., Mitchell, K., & Whitehouse-Tedd, K. M. (2015). Effect of post-gut loading time on the macro-nutrient content of three feeder invertebrate species. Journal of Zoo and Aquarium Research, 3(3), 87-93.

Teles, A. O., Couto, A., Enes, P., & Peres, H. (2020). Dietary protein requirements of fish–a meta‐analysis. Reviews in Aquaculture, 12(3), 1445-1477.

Velasco-Santamaría, Y., & Corredor-Santamaría, W. (2011). Nutritional requirements of freshwater ornamental fish: a review. Revista MVZ Córdoba, 16(2), 2458-2469.