My current 60gal tank consists of four fish: a black ear pangasius, a common pleco, a juvenile peacock bass, and a clown knifefish-most of which will outgrow my tank. So far, my only issue with the tank mates is that my CK is aggressive towards my pleco-not biting him or anything like that; more like shoving him out of the way. I know my tank is small for the fish I have-that's why I'm planning on upgrading when I can. But, with what I currently have, what fish would be good tank mates?