I just noticed my hooded Wrasse on day 3 of QT with a damaged or wounded fin. He seemed fine when I got him from DD. He’s by himself in a 10g going through TTM. If you look close his fine bone seems exposed. Is this an infection?
I'm not speaking as a fish doctor. But it doesn't look like a new wound to me. It looks quite clean with a defined edge. From the photo I don't think it's infected. How does it look in person? Ratty at all? If it's not infected, I wouldn't treat. But that's just me.