i have a four inch oscar who is always chillin in the corner of my tank and a little pail and when i got hime about 3 months ago he was a real dark black and a real bright orange and now he's a little gray and you can barley see his orange stripes. and i have no idea what it my be i feed him good i dont think i over feed or under feed and the tank is real clean but not to clean. so does anyone know what might be wrong