Can Plecos Digest Wood?

[Ulu]

Thanks for the updates.

I kept loricariidae which lived for 12 years without any wood. I'm thinking they might have lived 20 with it.

I have bogwood in all my tanks now and all my L's suck on it frequently.

 

[RD.]

Apparently the xylivores do not digest wood directly to extract nutrition from it, rather they have gut bacteria which does the breaking down and then the fish get the nutrition via the bacteria.

Thanks for the additional info, but what does that really prove? As previously stated many hobbyists, including a number of people on this forum, state that certain plecos such as panaques must have wood as part of their diet. Some even believe that elements such as lignin is an essential nutrient in their natural diet. This study doesn't prove either - it simply suggests that "Panaque spp. possess a number of morphological adaptations that could support the ability to obtain dietary supplements from a resident microbial community located in the mucus layer along the GI tract surface."

That may disprove some of German's assertions, but it certainly doesn't discount my point, which was that Panaque spp. do not require wood as part of their diet, as many hobbyists have believed for many years. The fact that a fish has the ability to degrade cellulose doesn't equate to a fish needing that as some form of dietary supplement, in captivity. In nature that would simply be considered a survival tool, no different than many other species that in nature have adapted to eek out an existance in various low nutrient niches.

 

[Ulu]

. . . they have gut bacteria which does the breaking down and then the fish get the nutrition via the bacteria. . . .

That's not how it works for humans too? Eating roughage?

 

[skjl47]

Hello; Two things come to mind. One from personal experience the other from a distant memory of my student days.
First; I had a common pleco in a tank without wood for a time. I also had a supplementary sponge filter in the tank for some reason. I think I moved the sponge filter from another tank and just hooked it up in that tank so it would have a place to be and not dry out. The sponge was pretty loaded as I did not clean it. The pleco grazed on it a lot very soon had the surface cleaned. It kept coming back to the sponge pretty often.
I sort of figure they graze on wood for pretty much the same as the sponge. Maybe not so much for the wood itself but for the biofilms and stuff that grow on a surface. I also figure an organic substance like wood will especially promote such surface growth even better than inert sponge.

The other is that best I can recall is that animals that eat cellulose have a symbiotic gut bacteria which does most of the digesting. I can not recall for sure but do not really think they consume the bacteria but more absorb the nutrients the bacteria excrete.
There are some harvester ants who feed grass to a fungus. The fungus digests the grass and I do think the ants eat the fungus. Sort of like when I grow tomatoes maybe.

 

[Ulu]

Most of my fish graze off the foam filters. It's a buffet of things.

 

[skjl47]

Most of my fish graze off the foam filters. It's a buffet of things.

Hello; When I am raising very young fry that have recently hatched out I have learned to keep a mature sponge filter in with them. Does a few good things in such a tank. The very young fry will graze on the sponge for a time until they get large enough to move on to other foods.

 

[TwoTankAmin]

I would just point out that the study I posted suggested the fish were not consuming the wood being broken down in the the digestive tract. Rather they concluded that their research suggests the fish my be consuming the bacteria that did the breaking down and not the wood.

(Bold added by me.)

Our results suggest that the P. nigrolineatus GI tract contains a microbial community that has the capacity to degrade cellulose and are likely to be involved in the breakdown of cellulolytic substrates. The fish may obtain energy by digesting this microbial population, a strategy that is consistent with recent studies using isotope tracking, which found that wood-eating loricariids are assimilating microbially-derived carbon [28].

 

[jjohnwm]

Very interesting links, thanks for posting...and thanks to TwoTankAmin for bringing it back to the top.

Having kept only a few species of Loricariids, it seems I must have lucked out. I had numerous pieces of driftwood literally ground down to a shadow of their former selves by these fish, and I always assumed they were just incidentally damaging the wood while gleaning the aufwuchs (one of my favourite words, right up there with schadenfreude...) When I eventually "learned" that they were feeding on the wood, I felt badly for the few individuals I had kept who never had much or any access to wood...although those fish seemed to live and grow as well as the wood-munching ones. The distinction between eating and digesting became a concern.

Now, I always had plywood tanks, waterproofed with epoxy, and I always fretted a bit about those abrasive mouthparts chewing through my epoxy and ruining my tanks. Not only did this never happen, but I rarely even see these fish working on the tank sides or back, despite the fact that I never clean those surfaces and allow algae and other goodies to grow unchecked on them. So, since I now "knew" that they ate wood, I reasoned that they confined their attentions to the driftwood that was easily ground down and eaten, finding the epoxy uninteresting. Maybe the epoxy has an unpleasant taste similar to that of older, uncoated aluminum beer cans?

With all the cool new Pleco-types in the hobby today, as opposed to a couple decades ago, it would seem that generalizing about stuff like this is futile, since we now "know" that various species are carnivorous to various degrees. There's probably a Pleco that requires uncoated aluminum beer cans in its diet, and we are waiting to discover it.

Tommy Lee Jones says it perfectly in Men In Black: A few hundred years ago we knew the Earth was flat...yesterday we knew we were alone in the universe...just think what we will know tomorrow.

 

[BurbeyTanks]

i just read this whole this whole thread and found a ton of info as L numbers are my favorite fish. I only have an L200 and an L190 (2”) at the moment. I saw someone mentioned the higher protein foods for the Panaque is that something to worry about or is that same protein beneficial?

 

[TwoTankAmin]

I am not sure if I provided a link to the study I mentioned. You can read the entire paper is you click the blue text in the citation below.

McCauley, M, German, DP, Lujan, NK, Jackson, CR. Gut microbiomes of sympatric Amazonian wood‐eating catfishes (Loricariidae) reflect host identity and little role in wood digestion. Ecol Evol. 2020; 10: 7117– 7128. https://doi.org/10.1002/ece3.6413