I have had my oscar for about 6 years and he is about 10+'' by himself in a 75 Gallon FW tank. I have left the tank pretty empty because he destroys anything and everything I have placed in it other than about 50-60 lbs of rock and a few large fake aquarium rocks. I am new to this forum and can send pictures. The "wart looking" thing on his chin has gone from a small ready to pop pimple to a pencil eraser shape, size, and collored growth. Any advise would help.