A buddy of mine had a single "O" in a 29 gallon....problem is little dude's not so little and cute and getting more expensive to feed. I came by to check him out and was stunned to see what a beutiful fish he wanted to get rid of. Now he's in a 75 gallon with a red and tiger "O" and now are getting along. Not their permenant home of course. Anyhow, just wanted to share the find.