My purple tile fish a few days ago had a small bump right ontop of his nose. First i thought maybe he smacked it on a rock but it seems to have gotten larger. My parimiters are were they should be except my nitrates which always stay around 20. He seems fine eats like a beast, and no other fish in the tank has it. I don't quarinten my fish but havent added anything new in the last six month except a bubble tip an. Any help is apprieciated