I have a 1+ year old Oscar and I’ve always taken good care of him and his tank with water changes weekly if not twice a week. Recently I noticed some pitting going on on the top of his head and around his nose as seen in the pictures. Over the past two weeks I have changed his diet to include healthier items such as frozen krill and beef heart, done massive water changes, added a little aquarium salt, kept all lights off to avoid stress, if any and medicated with API general cure. I have seen no improvement, if not a worsening in his condition and I’m not sure what to do. He’s currently around 8” long, in a 55G and running on a marineland c-220 with the carbon removed (for medication and also because I read that some people say that it can cause HITH)