i have a gold piranha in a 29 gallon tank and he has some sort of a white circle bump on his chin i think is is from rubbing up against the glass because i just got him yesterday and i was just making sure it was that i really dont think it is any type of disease or something that could harm the fish but if you could tell me if im right or wrong that would be great please respond asap he was 69.99 and i dont want to lose him