Help! Clownfish aggression

[maxemorris]

I have had a Midas Blenny in my 32G biocube for around 6-8 months now. I had him with a pair of large oclerous clownfish, and they unfortunately killed my baby tang. When I saw similar marks on my Midas, I knew they had to go and got rid of them immediately. I now have a pair of baby picasso percula clownfish, and after less than a month my Midas has the same maybe worse tearing on his top and bottom fins.

What should I do? I love him so much and don’t want to give him up, and I thought if I added new baby clownfish to a system where the Midas already has territory there would not be a problem. There’s no other animals that can harm him, unless you think a shrimp or snails could.

 

[maxemorris]

I should mention that I have not seen them fight, I’m only assuming since I can’t see any other way this would happen. I do have a powerhead in the tank, but it is very weak (500GPH) and has a plastic guard around the prop.