Agressive Clown Behaviour

I had 2 oc clowns and then I put two b & w oc clowns and man that was a stressful time as the large oc clown was biting on my smaller b & w oc clown. It would chase and bite the poor little guy all day long only when he was not around the larger b & w clown. I then put the aggresor in a noodle strainer for a few days. I released and after a couple of hours he went right back to doing the same thing. He got a trip to the lfs which is sad because the smaller oc clown needs a mate, so I will put in a smaller one soon. the b & w large clown sometimes reminds the oc clown whos tank this is now but he never bites.