Not sure what to do.. water parameters are okay, all the other fish seem fine. A week or so ago I noticed what appeared to be some damage to the side of the fish. I thought it was maybe he hit something in the tank and tore his skin a little. He seemed fine up to a few days ago then it started to look bad and his face got puffy. He's barely moving now, and mostly has been sitting on the floor and against objects in the tank. Please advise what I should do.