I commonly get asked what I’d feed different groups of pleco’s and it does vary by the pleco, Loricariid but also by what is available in your country. Some genera are more generalist and forgiving then others, some will withstand a less then ideal diet for maybe a few decades and others a few months/days.

While I would love to provide more details some I cannot list yet or am not entirely clear on some aspects of a species dietary ecology. So this should hopefully help for now.

I shall split it up by diet, some species might feed on a different diet to what you expect so please search for the genus/species.

The majority of Loricariids are algivores and detritivores so this contains the larger amount of categories.

Algivores

This is one of the largest categories as many Loricariids specialize in different algae’s, biofilms etc. But due to mode of feeding and availability of ingredients I will kind of have to generalize. Due to this the algae growing in the aquarium might be the wrong species so the fish might not feed on it, regardless any algae in the aquarium will not sustain most species long term.

Prepared diets:

• Repashy Super Green
• Repashy Soilent Green (you can add in extra algae powders to bulk it out, fishes seem to prefer this diet).

Making your own Algivore Diet

This is a trial as it seems Repashy is becoming unavailable in many countries. I have done many different trials and tests but am still developing something.

Nutritional ingredients:

These are the main ingredients and should make up at least 80% of the nutritional ingredients used but can makeup the whole diet minus gelling agents (Vucko et al., 2017). Percentages might vary, ideally try to include higher volumes of those highlighted in bold, not all will be available so try to include as wide of a diversity of possible. High spirulina content might take a while for the fishes to get used to. Seaweeds will need to be blended or might not be eaten.

• Chlorella algae (Vital)
• Spirulina algae (Vital)
• Seaweed meal (Vital)
• Kelp meal (vital)
• Wakame algae (vital)
• Nori (Vital)
• Bladderwrack
• Other human consumption seaweeds and algaes.
• Potentially mosses, never tried but are recorded in Loricariid diets.

Herbal ingredients:

These should be very limited excluding the mushrooms I wouldn’t go above around 1-2% per ingredient.

• Paprika, associated with red enhancing.
• Mushrooms, dried or powdered while not entirely known it is potential they feed on fungi in the wild. While edible mushrooms might not be the same taxa it does seem to be a taste enhancer for fishes at least.
• Basil, associated with improved physiological and immunological health while being an attractant (Mansour et al., 2023).
• Ginger, feed attractant and immunological support (Ahmad et al., 2024).
• Garlic, I don’t always use it but feed attractant with potential immunological support but can cause liver damage.
• Seeds, particularly found in the guts of Hypancistrus and potentially Peckoltia. Higher in fats and proteins.

Gelling agents:

I would recommend using carrageenan powder due to it lasting longer then the alternatives. I would use this regardless as to whether it is a carnivorous or herbivorous diet.

Who are the algivores that we keep?

• Ancistrus
• Baryancistrus
• Dekeyseria
• Farlowella
• Hemiancistrus
• Hypostomus
• Isorineloricaria
• Lamontichthys
• Lasiancistrus
• Nannoptopoma
• Otocinclus
• Panaque
• Panaqolus
• Parancistrus
• Parotocinclus
• Pseudancistrus
• Pseudorinelepis
• Pterygoplichthys
• Rhinotocinclus
• Spectracanthicus zuanoni/punctasissimus
• Sturisoma/Sturisomatichthys

This diet will cover most of Loricariidae but particularly these genera, while they might be also more detritivorous in the wild this is the closest we can get to their natural diet.

Regarding Hypancistrus, Peckoltia and potentially Panaqolus I would add seeds to their diet and maybe look at the addition of infrequent invertebrates.

A little more carnivorous

If you want to increase the volume of carnivorous ingredients, Loricariids don’t consume fishes in the wild so we will be looking at invertebrates. Due to the presence of thiaminase in some ingredients I do not recommend the frequent use of mussels or prawns.

So as you’re looking more into carnivory I would increase the volume of these ingredients, luckily for carnivorous ingredients you could feed as a frozen or live food they have to forage.

Ingredients:

• Daphina
• Brine shrimp
• Tubifex
• Bloodworm (Chironomatid larvae).
• Cockels
• Mysis
• Red plankton
• Ant eggs
• Earthworms
• Cyclops
• Whiteworms
• Blackworms
• Vinegar worms

What about molluscivores?

Scobiancistrus, Leporacanthicus, Pseudohemiodon, Loricaria and Planiloricaria are likely capable on feeding on mussels and occasionally this is proven. A diversity of snails can be trialed for the Scobinancistrus and Leporacanthicus larger species such as Ampulluridae would be ideal as these are evolved to extract snails from their shells, escargot snails that are not treated with garlic would be interesting to explore. For others then smaller snails whether it be juveniles of harder species of pest snails.

Plant eaters

Realistically many Loricariids do not consume traditional plants so often these are best to identify if a fish is feeding or not. Some very broad generalist taxa might consume more like Pterygoplichthys and Hypostomus.

Using other premade foods as a base.

This is largely only possible with gel diets but possibly some pastes. The main rule is not to add so many that the gelling agent doesn’t hold as well as it used to but also this will depend on how fast your fishes feed.

What base diets can you use?

• Repashy. It does have a wide range of other ingredients.
• In the Bag Tropical Fish UK’s pleco pops. Very strong gelling agents and true carnivorous and herbivorous diets.
• EBO pastes
• Tropical’s gels/pastes

Testing diets to identify if they are being used.

Glass petri dishes can be ideal here as they sink and are inert, you can pipette or place food on and ideally it will not be disturbed over the time you are not observing the food being eaten. Therefore it can be a reliable method of identifying what is taken and what is not.

References:

Ahmad, I., Irm, M., Ahmed, I., Haoran, Y., Taj, S., Bhat, T. A., … & Amin, A. (2024). Role of ginger in fish nutrition with special emphasis on growth, health, gut and liver morphology. Journal of the World Aquaculture Society, 55(6), e13101.

Mansour, A. T., Diab, A. M., Khalil, R. H., Eldessouki, E. A., El-Sabbagh, N., Elsamannoudy, S. I., & Younis, N. A. (2023). Physiological and immunological responses of Nile tilapia fed dietary supplementation of sweet basil ethanolic and aqueous extracts. Frontiers in Marine Science, 9, 1064455.

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.

Loricariidae, also known under the common names L numbers, whiptail catfishes and pleco’s are popular fishes within the aquarium trade. Many people will come across the problem in their new fish where they will not eat and in fact they might never eat.

Worming

The first sign might be that the fish might have a concaved stomach and the first solution will be to worm the fish. I doubt this is the usual cause of the concave stomach in Loricariid’s but it is worth crossing out, Loricariids do quite frequently have parasitic worm’s (usually nematodes rather then Annelid’s) in the wild and these will maintain at a low level (Borges et al., 2018). If a fish is stressed such as from import this parasite load can become much higher then a healthy level. So there is logic in worming fishes when they arrive and most stores do this. Most wormers cover different internal parasites but the most common would be containing praziquantel, levamisole and flubendazole (do not use with stingrays). I would personally advise definitely not using more then one as they do all have side effects. Generally wormers need to be repeated after a week to cover the parasites lifecycle.

The importance of getting the fish feeding.

While a rounded and healthy diet is important for wild caught fishes particularly they do need to feed. It is quite a large jump for many from a wild diet to a captive diet and many might not even identify it as food.

More importantly it is possible that the gut flora, microbes will start to decline in number while they are not eating and for shipping this is useful but not for keeping the fish. One possible thing that could help this is rather then adding them to a clean quarantine tank is to one where other similar species have lived, there is likely a benefit from those fishes waste in rebuilding that gut flora lost after shipping.

What should I feed my fish?

First identify what they eat, so their natural diet. While most diets contain the steryotypical fish/insect/krill meal, cereal, vegetable and minimal algae diets this is no issue in the short term but many wont touch these diets at first. So regardless of long term them being vastly different from their natural diet and homogenous whether you have a Trophius, Loricariid or angelfish they actually are the same (Vucko et al., 2017); they can also be unhelpful.

One day I will create a proper list of what Loricariid eats what as far as we know but currently I cannot. I do have articles on some commonly misunderstood fishes; Hypancistrus (zebra, king tigers, queen arabesque, snowball pleco, L236 etc.), Panaque and Panaqolus (royal pleco’s, flash pleco and the clown pleco’s), substrate dwelling Loricariinae (Pseudohemiodon, Planiloricaria etc.), Baryancistrus (gold nugget pleco, mango/magnum pleco, snowball pleco), mollusc specialists (Scobinancistrus, goldie/sunshine pleco, vampire pleco, galaxy pleco, Leporacanthicus), Chaetostoma (Rubbernoses and one of the bulldog plecos) and finally algivores/detritivores. Maybe some more will be created in the future.

This is important as feeding an incorrect diet can lead to bloat and other issues, it has been commonly noted when Hypancistrus are fed a wholly carnivorous diet.

Carnivorous species

This is only for true carnivores but aspects of this can be fed to others in small numbers with care, avoid it with some of the more extreme algivores such as Ancistrus, Chaetostoma, Baryancistrus etc.

Mussels and prawns are very good for getting a fish feeding at first but the issue with these two food items at high in thiaminase and therefore degrade thiamin, vitamin b1.

Generally for this reason I’d advise a range of frozen foods and for some larger species earthworms might not be a bad choice.

Algivores and Detritivores

This includes most Loricariids that people keep to some degree but the specialities within their diet are best looking at later.

These are definitely the most tricky to get feeding at first and I often give a range of options even at the same time. Generally I’d offer that dry/gel diet once or twice a day and vegetables replaced every 12-24 hours depending on how quickly they are braking down.

For dry/gel diets I’d offer certainly Repashy soilent green if possible as I’ve never had a fish fail to give it a go. Later on I’d bulk it out with other ingredients such as algal powders, you could do similar with other gel diets but I can’t say fishes are going to take up them as well. At the end of the day whatever they are eating in the short term is worth it. Remember vegetables and similar are more treats as do not even closely replicate their wild diets.

Vegetables and other easy food items you can leave in for the fishes:

Later on and narrowing down the diet

While whatever they will eat is generally the best rule as they are acclimatizing over the first few weeks and months. Afterwards I would look to narrowing down their diet to what they would feed on in the wild as in the articles mentioned earlier on.

Is the setup right?

This sometimes get’s forgotten but a major part of why a fish might not be feeding could be they are not getting to the food. Loricariids are slow to feed, some might take hours even without lights to feed and this can make some tankmates ill-suited. Some tankmates might work better where if needed you can remove them to another tank so that is worth considering particularly for many cichlids, many shoaling species in very high numbers or quite a few live numbers.

References:

Borges, W. F., de Oliveira, M. S. B., Santos, G. G., & Tavares-Dias, M. (2018). Parasites in Loricariidae from Brazil: checklist and new records for fish from the Brazilian Amazon. Acta Scientiarum. Biological Sciences, 40, 1-9.

Chandra, O. P., & Qureshi, Y. (2023). Importance of mushroom supplementation as a prebiotic amalgamation in fed diet of improvement of weight gain (WG) in Nile Tilapia,(Oreochromis niloticus). Journal of Pharmaceutical Negative Results, 1681-1687.

Dawood, M. A., Eweedah, N. M., El-Sharawy, M. E., Awad, S. S., Van Doan, H., & Paray, B. A. (2020). Dietary white button mushroom improved the growth, immunity, antioxidative status and resistance against heat stress in Nile tilapia (Oreochromis niloticus). Aquaculture, 523, 735229.

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.

Omoregie, E., Igoche, L., Ojobe, T. O., Absalom, K. V., & Onusiriuka, B. C. (2009). Effect of varying levels of sweet potato (Ipomea Batatas) peels on growth, feed utilization and some biochemical responses of the cichlid (Oreochromis Niloticus). African Journal of Food, Agriculture, Nutrition and Development, 9(2), 700-712.

Sánchez-Velázquez, J., Peña-Herrejón, G. A., & Aguirre-Becerra, H. (2024). Fish Responses to Alternative Feeding Ingredients under Abiotic Chronic Stress. Animals, 14(5), 765.

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.

Zakaria, Z., Abd Rasib, N. A., & Tompang, M. F. (2021). Spent mushroom substrate based fish feed affects the growth of catfish (Clarias gariepinus). In IOP Conference Series: Earth and Environmental Science (Vol. 765, No. 1, p. 012082). IOP Publishing.

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.

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.

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.

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.

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

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.