it looks like a physical scrape, not too deep but took a fine layer of white off the top of his head. the tank is right next to where i sit, and last night i noticed a quick splashing sound up near the corner top of the tank where he sleeps, like he got spooked by something, i'm thinking he scraped his head on the cross brace. i don't have anything in the tank that would have attacked him. i'm just bummed because he has perfect colors and markings and i hoping that it will turn back white. is there any type of food additive that helps in healing?