Yeah I know they aggressive but there are worse. (Undulate, Queen, Titan). At our LFS I've seen Picassos and Nigers act more aggressive then clowns he has had; our niger is a weenie but he had one that he had to remove and put in his 180 curing tank.....nasty. Although these fish are know to have a jekel and hyde mentality we'll have to see. There's a guy on grimreefers who has an undulated, clown, niger, picasso, cosshatch, damsels and some other fish in his tank and has had no problem. The fish are well fed in a large tank which probably give them less room to get bored and start fighting. We were thinking of a clown,picasso and a dotty that is larger than the two. They would be going in our 90GL. then into our 180 when they get bigger.