I have 5 of them waiting to go into my high current river tank. they like fast clean water that is well oxygenated. they are mainly going to eat algae, and lots of it! you can supplement with algae wafers and flake foods but they are mainly going to eat algae and the little microscopic critters that live in the algae. six would be a great number. I notice that they are more active when there is more of them. they will play "king of the hill" for the best algae feeding spots. they are fairly sensitive so make sure your water stays extremely clean, well oxygenated, temp around 65-75 degrees (they like it a little cooler) and maybe have a couple powerheads to create some fast water current as they come from fast moving mountain streams.