Do plecos and otos add to the bio load

ABSOLUTEY , they add to the bioload... plecos especially

Actually, they don't recycle or absorb nutrients, this is an all too common myth. They are just like other fish, they eat fish food and they poop fish poop. The young of many species of plecos eat algae, but as they grow older they need to be supplimented with protein. Otos eat algae and need to be subsituted with veggies and algae disks once the algae is gone.

Otos and plecos do not eat other fish poop, to do so constantley would be hazzardous to their health.

While the addition to the bioload on otos is fairly small as they stay small and are not heavy waste produces, BUT it is just as much as any two inch tetra.

Most plecos, on the other hand, are heavy waste producers and need very large tanks with heavy filtration. Many also grow larger than 12'' and do so very quickly, adding even more need to good filtration and large housing.

As for the inch/gallon rule... it's not a "rule" at all, but rather something that has been dragged out far to long. Here is a post regaurding the issue posted by Richer in the FW newbie forum,
http://aquariacentral.com/forums/showthread.php?threadid=26409

Yep they definalty should.

Plecos are "poop machines" not sure about otos

Any fish will pass waste etc therefore adding to a tanks bid-load.

There was an interesting stickiy about the flaws in the inch per gallon rule (if thats what you where refering too?)

basically fish are 3D so allthough a fish maybe 2ins long if its just as wide it will produce more waste than a 2in ong thin fish, if that makes sense. The only fishes that really follow this rule are things like little neons and other small tetras

The most important factor is to make sure that the fish(s) have enough space and the filtration is upto the job

What have you in the tank at the mo?, how big is it?

EDIT: PumaWard, You beat me to it . Boy you must type fast

Everything that needs to be said has been spoken already, but GOD yes! Plecos in particular... they are horrible when it comes to fouling up a tank’s water.

Everything animal or microbial alive in the tank adds to the bioload. Bacteria (aerobic), fungi, infusorians, nematodes, copepods, snails, shrimp, fish - one and all are contributors to using oxygen and releasing wastes. Healthy plants generally are more plus than minus on that scale, but unhealthy plants also add to the bioload.

That's true! A rotting plant is bad news! I have a foot long pleco in my 75 and he DEFINITELY adds to the bioload. He is a little pooper! Plecos by nature have to eat high quanities of roughage in their diet. I feed mine zuchinni, driftwood to eat on and sinking algea pellets.... I could tell when my new tank was finally mature enough to handle his poo. His poo was all gone and broken down by morning, instead of long strings of it on the bottom of the aquarium that I would have to siphon out on a daily basis.

Otos don't add much to the bioload b/c of their small size...