I know of atleast 2 people that have a dwarf lion in their reef tank! You just have to watch them and what you put in your tank with them! My friend keeps his with a cleaner shrimp and i have watched the shrimp clean the inside of the lion fishes mouth! If you do deside to keep one make it the last fish you put in your tank! Get your inverts and all before him! Also keep him feed and he wont eat his tank mates!!