My parents recently got a Tiger Wardi Goby and the little fellow is in quarantine. He's been doing fine so far, but within the past couple of days he had what looked to be a bruise on his lip which has formed into what (to me) looks like it's rotting off. None of us have any idea what could've caused this or if it's an injury or a disease. My only thought is that maybe it touched its mouth to the heater in the tank and got burned. We've been giving it Metroplex medicine with its food and it's eating, but I feel horrible for the little fellow. Any sort of ideas on what this might be or how to best treat it would be greatly appreciated.