I recently adopted this angelfish from a local Facebook rehoming group. He’s in quarantine with two other juveniles for about four days now. I did my water change this morning and noticed he was breathing heavily, tested my water from my drain buckets and parameters read normal. Came home to find what looks to be some sort of lesion or peeling of the slime coat? It almost looks like sunburn when it peels on his head and something in his fin. I’d like to treat him but I need to know what this is first. Only other thing he’s been doing is slightly heavy breathing and lack of appetite, which I was at first attributing to him being stressed and settling in the tank.