As the title says.However,please be reasonable. Don't say arowana,because that is not a feeder!And yes,many small fish could,but is it really worth it?Maybe more common types.For example here is what I use: rosy reds,guppies(not the fancy kind),and platies.What about you?P.S. I know many feeders harbor diseases and stff,but this is a time when its like if you have to.