i have a red tail filefish in a fowlr 50g tank. last few days hes been resting against rocks at the bottom of the tank. Now today ive noticed hes got one small white patch near his breast fin. He has not eaten last night or today. tried feeding brine shrimp and pellets. he moves every once and a while but today when he moves he does flips and turns and spends most the time upside down. water specs are stable as well. any help is greatful.