Well, there are other clowns that are more aggressive towards eachother and other fish of there species.. but generally the ocellaris are pretty nice. Don't get me wrong though, the occasional bump or bruise or nick in a tail wouldn't be out of the ordinary for these fish if they are together. But usually, if you have a good size tank.. and they don;t like eachother, they will separate and stay in their own little corners. (Ask thincat. His clown has a nice hideout behind a pump lol.) Just think of it this way; the bigger the tank, the more room they have to be away from eachother. The smaller the tank, the more they are going to see eachother, and fight over territory, or anything for that matter. In my opinion, i've found the ocellaris to be nicer than other clowns, but as said before, they still have their quarks.