Just to add my story in lol, I had two pairs of clowns, orange oscellaris and B&W oscellaris and they were fine for a few months. BUT overnight it seemed to change and the orange ones started attacking the b&w's. They had to be removed that day or they would have killed the other pair. And this was in a 125g tank so there was definitely enough room but still didn't work.
180g Reef - 60g Rimless Reef -90G FOWLR- 125g Malawi Cichlids- 40b REEF- 34g Fresh Planted-working on- 20L FOWLR- working on
I have a mix of many different saltwater fish amongst my tanks, but I love my Tangs most of all.