I use to have a 20 gallon tank and got 2 Ocellaris Clownfish as my first fish. Any fish I tried to add after that my Clownfish would harass to death. They killed a total of 3 fish that way in the 20 gallon. I now upgraded to an 80 gallon tank and added my Clownfish and then 4 Chromis. The Clownfish now harassed 2 of the Chromis to death by chasing and nipping at them. I'm getting ready to add some expensive fish now but I'm nervous as to the Clownfish harassing the new fish that I get to death. What can I do?