PlanetCatfish.com

I've been told that most cories are low waste producers.

However, are some more waste-productive than others? IE, would a school pygmy cories, due to their tiny size, have less effect on a bioload than, say, a school of bronze cories?

Well, I have always read that for their size, corys produce a fairly large amount of waste. This is true for most types of catfish.

And yes, the smaller the cory, the less waste they will produce. A school of 10-15 full grown pygmy corys would have less effect on the bioload than say a school of 5-6 full grown bronze corys.