u/conithepirate

I noticed one of my puffers has a "wound" on his head. Hie would you guys treat it and what with?

Right, I'm out of ideas. I had this beautiful guy (not right now) for over a year and the past few weeks he really went downhill. I treated him for a hole in the head (see pic) twice. He lives in a 200L tank with shoalers, gets a variety of food mixed with garlic guard & vitamin.The tank has a big airstone in it, runs on Eheim Professional 4+ filter and TMC Vecton UV Steriliser. I moved him to a smaller tank so he can be on his own for a bit and recover but I honestly don't know what to treat him for at this point. He is also constantly opening and closing his mouth so what on earth is going on?