Kole Tang Fin Damaged

[Boochika]

I wrote about the Kole tang I received a few weeks back and it's been doing really well. Eating a lot of mysis and picking all day on the rocks and glass. I noticed when i received it it had some damage to it's upper and lower fins. I figured OK new fish probably some damage from shipping or what not. I've kept and eye on it and it didn't seem to get better but I wasn't too worried.

Fast forward to this morning I notice a crescent shape taken out of the fish's fin and it's much larger and noticeable than anything i've seen in the past. The tang will chase other fish very rarely, but is never chased or attacked by other fish itself. I don't have any anemones or large inverts that could cause this damage either. I'm looking for some help as to what could fix this issue and heal the fish. It seems happy playfully swimming around all day, but I'm not fully sure if it's settled in yet.

I have an 48" x 18" x 24" tank.

Parameters are as follows:

Temp at 78-79
Ph at 8.2
7.5-8.5 DKh
No3 around 2-4
P03 at .03
salinity at 1.0259
Ca at 430
MG at 1300

 

[vetteguy53081]

Something or someone in tank is being aggressive and without knowing other tank mates, im guessing clownfish or other tang.

 

[Boochika]

I do have a clownfish in there, but I have never seen him go after it. perhaps when i'm not looking. Any tips to stop it?