No clowns really shouldnt be that agressive, but it does happen. Thats what happens when you buy a pair that has been a pair for a while, generally they are the only fish in the tank and then once noobs come in they get crazy. My advice is to trade them at your lfs
for 1 large occy clown and 1 small occy clown. They are less agressive and wont fight if there is a big size differance. Good luck!!