Panaque/Pleco feeding discussion (split from Science News)

[Janne]

But, if the fish are able to survive on wood alone it would be softer woods that would allow for this, and yet, this has not been observed.

I forgot this yeasterday, if you have an aquarium dedicated to only larger Panaque species and good filtration you could try to feed them old pieces of Alder (Alnus sp) that is a soft wood. They will consume it rapidly and it will disappear quite fast, I only recomend this for fanatics because in comunity tanks and aquarist's with not so much experience should not even try to use Alder.
I have never tried to only feed them soft wood so I have no idea if they would survive or grow in the long term.

Janne, what kinds of conditions do you think help promote Panaque growth? That's interesting that you say slow growth is a myth. My own sample size of one Panaque certainly isn't exactly good evidence to support that they're slow growing.

There have been some studies that show water quality to be more important than food availability w/ re to growth.

This is something that profesional breeders have known since decades, a good breeder change at least 50% up to 100% of the water every day in their growing tanks. Breeders that use high tecnology and have enough money build a filtration system you only can dream of but still change quite high amount of the water. Food VS water is the most important for breeders, that would be interesting to know what substances in the water that affects the growth... it can't only be nitroge'n products. For some years ago there was a discussion if keeping many fishes in a small water volume VS releasing pheromones affecting their growth, maybe also something that would be interesting for a study.

Than it can be something wrong with a fish making it grow slow, parasites or problem with their intestines or other problem.

Once again I think this may be both by sp and specific environment. Sand consumption makes a lot of sense from a nutrional stand point in very mineral poor waters like those originating in the Guyana Shield. This should be an easy one to test for actually.

Almost all drainage in the Amazon is very or extremely poor in minerals, Andean rivers is little more richer in minerals but still poor except a few exceptions.

Janne

[DP German]

Regarding whether loricariids consume the same foods among seasons (wet vs. dry), I think that stable isotopes help with this. The Panaque and H. pyrineusi I caught in Peru were slightly different; whereas the Panaque showed identical carbon and nitrogen signatures among their plasma proteins and red blood cells, the H. pyrineusi had significantly different carbon signatures among their plasma proteins and red blood cells.

This is important because at a given time there is a certain "pool" of carbon composing an animals tissues and they get this carbon from their food. The carbon pool turns over four times faster in the plasma proteins in comparison to red blood cells. So, similarity in carbon signature among these two tissues suggests that the fish have been eating the same thing for at least four months (the turnover time of red blood cells), whereas a difference among the two suggests that the fish have changed their diet in at least the last 30 days (the turnover time for plasma proteins). Although I have problems with the previous stable isotope paper on Panaque (again, contact me if you want to discuss this), the cool thing was that the otolith isotopic values suggested that the Panaque had a similar diet among wet and dry seasons, whereas Hypostomus regani had a variable diet.

So, it looks like at least the Panaque have consistent diets, whereas other loris may have more variable diets, including the wood-eating H. pyrineusi. I also have data showing that Pterygoplichthys disjunctivus' diet in Florida is highly variable. Their carbon and nitrogen signatures from a variety of tissues vary widely through time showing that these fish are generalists and can consume a variety of foods. This is what you would expect from an animal that makes the perfect invasive species (http://www.plecoinvasion.org/index.htm).

Cheers,

Donovan

[racoll]

http://www.plecoinvasion.org/index.htm

Thanks for that link Donovan. I am working on invasive Pterygoplichthys and I will get in contact with Krista Capps at Cornell about the project.

[DP German]

That's awesome Racoll! I am quite interested in their invasiveness. They are ALL OVER Florida.

Krista is a friend of mine. We collected fish together in Peru and have communicated quite a bit regarding loricariid biology.

Where are you working in Pterygoplichthys? They aren't in NZ are they?