My New Pyramid Butterflyfish

[Mike612]

I just got the butterfly Saturday. He has honestly been at the store since April or May and nobody bought him. He eats like a pig in my tank and will eat everything from frozen shrimp to flake food. It leaves the coral and inverts alone. My concern now is that I just noticed he has something white around his mouth. It doesn't look like ich. It kind of looks like meat coming off or something. My Kole Tang has been chasing him a bit but he never went for the mouth. My water parameters are as follows: salinity level 1.024, pH 8.3, ammonia nitrate and nitrite 0, temperature is 79. Any ideas?