Serious Clownfish Agression

Hi all, I have had my two ocellaris clownfish for 6 months now and have just had to place one in a breeding trap because the previously established female has bitten his top fin off and reduced all the others to tatters. What can I do to help him? Do I need to place him in a QT tank to medicate him if he needs to be medicated? Does the other need to go?



Thanks, The Cowfish