FWIW...we started with 40+ in a densely planted 90. Ended up with 2. I don't know if it was a lack of food--we fed snails, live and frozen brine, black worms and frozen krill--or if they killed each other off. I suspect some of the former when there were lots, the latter once it dropped below about 10. Despite our best efforts to make sure every fish had fat bellies each day, numbers just kept dropping. Heartbreaking. They were awesome to watch display pack behavior hunting live food, but spent an awful lot of time brutalizing each other.