well dang. the treatment I was gonna suggest was raising the salinity to 12ppm for a few days. it irritates him and it makes it harder on him to swim, but it kills any bacterial, fungal, or similar problem without causing too much pain on the fish. I treated an oscar like this for 3 different things and he ended up dieing a year later from hith that this wouldn't fix. it did give him one more nice day before he died though... I miss him he was 3 and a half years old and nicer than any other fish I've had.