IMHO, all clowns get aggressive as they mature. It's their nature. Clowns like maroons and polymnus simply get bigger than most so they can cause more damage when they act up. I don't think it's because they are any more or less "aggressive" than other clowns. Even different fish within the same species can have different personalities. The nastiest clown I've ever had, which I still have, is a 3" clarkii. Evil little fish.LOL