Ick? Fin rot? Or just nibbles?

[Armani]

So I haven’t noticed it until today but I’m not sure if it’s anything please help me out!! Is this ick Forming? Or maybe another fish has been biting his fin? When he first got in the tank my Nemo and him fought for a day or two and after that everything was fine..it’s been about a week or 2 and td I just noticed this.....

 

[EmdeReef]

That looks like it could’ve been a wound, with secondary bacterial infection.

Antiseptic bath in acriflavine or ruby rally would be good followed by abx treatment.

In the long run it’s critical to deal with the aggression.