Mine is currently in a 45 gallon by himself in my bedroom. I had him first in my 75 and then my 215 tank. He was fine with corals and the smaller fish but he got VERY territorial with the larger fish (betta, foxface, regal) and I had to separate him to avoid aggression. He will practically eat out of my hand and is a great fish he just wants to be the alpha fish in the tank it seems - no crustaceans would be my afvice though my coral banded shrimp lived with him for almost a year with no incidents - the CBS is very large and ornery and I think that partially contributed plus the tusk was kept well fed.