Clown question: My first two inhabitants were a pair of true percula clownfish from Liveaquaria which have done great, very peaceful and get along fine with my other fish. The only downside is that they mainly stay at the top of the tank, rarely venturing down more than halfway to the bottom of the tank. I would like some which hang out down among the rock and corals. Wondering about adding a pair of ocellaris clowns if that would not cause trouble. Am I asking for warfare and chaos introducing a second pair? I only have a 55g tank. Any and all comments would be welcome.