flesh is being eaten away!!!

[Dough]

I have a 7" feather fin catfish. Its skin is being eaten away from his body. he is in a 210g tank with a colony of geos and a few sevs. I just recently had an issue with my tank and lost about 10 fish. I treated the tank with some anti fungal and anti bacterial meds. thats when the issue started with the cat. I removed it and put in to a seperate tank for about 3 weeks. on the 210g I have now done 2 15-20% water changes after the meds. all other fish are doing fine. I put the cat back in the 210g after he was all healed up. now a few days later he is getting these same sores or flesh eating issues. tank perameters are good. what might be the issue. Thanks in advance for the help.

[Elle]

This is a longer shot, but is one of the other fish maybe picking at him? If he healed up in the QT tank but is having issues in the main tank, that may be something to look at.

[Dough]

I dont think so. Haven't seen any other fish bother him