We have three cories in our ten-gallon. I won't be putting any in our next tank. As someone else pointed out, they don't clean up the garbage from other fish. You have to feed the cories their own food. If you really want a garbage crew, invest in ordinary ghost shrimp. They'll eat everything the cories will eat and then some. We also have apple snails and trumpet snails in our tank. Nothing remotely edible lasts very long on the bottom.