Do plecs need wood?

Ichthys

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Nope. Plecs (the Loricariidae) are a very diverse group that contains many different feeding types. Only Panaque, Panaquolus, and the Hypostomus ‘Cochliodon’ group have the dentition required to rasp away wood itself, but even they cannot digest it. They eat the biofilm that grows on it, and the wood itself passes right through them.

Poster made by ichthyologist Rebecca Bentley.

0F5670CF-8165-49C7-A39D-99A32E96CA17.jpeg
 
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I have never kept any of the Xlivores, but I have kept or keep and have bred or breed:

Tank strains of bristlenose - Anxistrus
P. compta -
H. zebra
H. contradens
H. L236
H. L173b
H. L173

In 100% of the tanks holding the above plecos I have always had a decent amount of wood. Not for eating but for hiding in or under. Or sitting on at times.

As to what the xylivores eat, "these fishes live from the rotting bacteria, not from the wood itself." From Plantcatfish:
Gut microbes of wood-eating Panaqolus and Panaque

Research paper:

McCauley, M., German, D.P., Lujan, N.K. and Jackson, C.R., 2020. Gut microbiomes of sympatric Amazonian wood‐eating catfishes (Loricariidae) reflect host identity and little role in wood digestion. Ecology and Evolution, 10(14), pp.7117-7128.
https://scholar.google.com/scholar?...s_sdt=0,33&scillfp=7740930202872217750&oi=lle

I saw Shane at the CatfishConvention last October. :)
 
My understanding has always been that some species do require wood, not as nutrition, but it has something to do with the bacteria (as TwpTankAmin said) and this also applies to Ancistrus species (Bristlenoses). These Ancistrus species require wood fibre in their diet. I wrote this in my profile of Ancistrus a decade ago, it may have come from Armbruster (2004), I really cannot remember.

Armbruster, J.W. (2004), "Phylogenetic relationships of the suckermouth armoured catfishes (Loricariidae) with emphasis on the Hypostominae and the Ancistrinae," Zoological Journal of the Linnean Society, 141, pp. 1-80.
 
According to Ingo Seidel, ancistrus are considered Aufwuchs feeders. At least in his Book on L-number fish states that. They are eating the algae and all the critters living in it.
Adopted German term meaning 'surface growth' used to describe the aggregate of plants, animals and detritus adhering to solid surfaces such as rocks or vegetation in aquatic environments.
 
According to Ingo Seidel, ancistrus are considered Aufwuchs feeders. At least in his Book on L-number fish states that. They are eating the algae and all the critters living in it.

Agree, I may have misled previously. What I intended saying was that Ancistrus need wood to graze, and the wood has some bacterial function in their digestive systems. Sorry, didn't mean to suggest their diet was the other. Wish I could remember where I picked that up; some of my profiles (there are more than 200 of them on another site) did not have particularly good references, totally my fault.
 
As others have stated, catfish don't use wood as a food source. They graze on its surface to consume the biofilm (aufwuchs). My Bristlenose apparently loves the black algae that recently started growing on my driftwood. The driftwood is a very dense hardwood. Subsequently, he deposits large amounts of black colored feces in the form of pellets all over the substrate. These pellets consist primarily of indigestible wood. I know this because the pellets are so dense most of them cannot be vacuumed up without also vacuuming up the gravel substrate.
 
Is a pleco a pleco is a better question. We try, when we are new to the hobby, to oversimplify nature and to ignore biodiversity. The number of fish we call plecos is mind blowing, and the name is an anvil around our necks. I used to process my driftwood with what I had received as a Panaque species - I'd put them to work cleaning any thing I'd missed and they'd poop dark sawdust. When all my tanks had enough wood to look like flooded forests, their habits became a problem and I passed the group to a friend who was starting his own project. I hope that somewhere out there, the sawdust is still falling.

Many other species have had no interest in wood. We overgeneralize too much.

As I move along through the hobby, I've been learning how many of the Cichlids I like are detritivores - eaters of stuff on the bottom of streams. Here I was, giving them careful diets, and there they were, digging through the bottom of the tank looking for delicacies. I figure the woodcats are like Geophagus, who sift sand for their food, but don't eat it as nutrition.
 
As I move along through the hobby, I've been learning how many of the Cichlids I like are detritivores - eaters of stuff on the bottom of streams. Here I was, giving them careful diets, and there they were, digging through the bottom of the tank looking for delicacies. I figure the woodcats are like Geophagus, who sift sand for their food, but don't eat it as nutrition.

It’s like when we go away on holiday and leave our fish to fend for themselves, and when we get back the tanks are cleaner than when we left, and the fish aren’t even thin. It’s like they’re better off without us sometimes... and then they see us and go “I’m starving, I need food” and I’m like “oh really??”
 
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Nope. Plecs (the Loricariidae) are a very diverse group that contains many different feeding types. Only Panaque, Panaquolus, and the Hypostomus ‘Cochliodon’ group have the dentition required to rasp away wood itself, but even they cannot digest it. They eat the biofilm that grows on it, and the wood itself passes right through them.

Poster made by ichthyologist Rebecca Bentley.

View attachment 312103
Though they don't digest the wood itself (don't feed on it) I think the vibers passing through their intestials is an essential part of their "need".
 

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