You could have a small shoal of hoplo catfish - the mega-cory. It looks and acts kind of like a big corydoras, but it is even more active. It is a total glutton, but peaceful. For some reason they don't seem to prey on even tiny little fish (I have had lampeye killies in a tank with a hoplo cat around 3-4" long for a month or two, and none were eaten. It won't even kill a ghost shrimp) unlike most catfish.
Figured I would mention it because no one else did yet.