Tang with discoloration near pectoral fin

[SgtIcedog]

I had this tang in QT for about two months. I am new to the QT portion of the hobby. I was lucky enough to go 4 years with adding fish straight to main tank and nothing happened until luck ran out. So now I am being cautious with that being said I did the Cupramine treatment and two freshwater dips afterward. the spot was dark in color but 4 days after the dips they turned lighter. In the mornings when the light turns on it’s harder to see but then becomes more visible.
Can someone share with me what this is?
What is the next step?

 

[vetteguy53081]

Looks like post injury but if in quarantine, what treatment are you using in quarantine?
This may lead to bacterial at worst case

 

[SgtIcedog]

Currently no treatment is being used because this is first time encountering this. After Cupramine treatment which ended two weeks back I just been watching him.

 

[Jay Hemdal]

Currently no treatment is being used because this is first time encountering this. After Cupramine treatment which ended two weeks back I just been watching him.

Welcome to Reef2Reef!

That looks like a post injury bruise to me. Is the spot getting larger? If not, I wouldn't try any treatment. If it is growing larger, that is a sign of possible infection.

Jay

 

[SgtIcedog]

Welcome to Reef2Reef!

That looks like a post injury bruise to me. Is the spot getting larger? If not, I wouldn't try any treatment. If it is growing larger, that is a sign of possible infection.

Jay

It’s not getting any larger. He is eating and acting fine. Thank you for the help.