I have heard that you should only keep 2 clowns in a tank. But I may be wrong which 9 out of 10 times am.
I would get Green Chromis. They are so call but make sure you get about 4-6. They are school fish. I still have 1 damsel in my tank and he knows better then to mess around with my clowns. He minds his own buisness. When I had a couple of them in there, thats when they are little A-holes....
-Paul
-Paul