at the store he was in smaller tank so thats ok i am feeding sinkin pellets i try to put one in his mouth but he turns around he is black now i dont know what to do
Can 't help you if you can 't give basic information
Sent from my iPhone using MonsterAquariaNetwork app
Honestly, I would give your Mbu back to the store or to perhaps a local friend who has more experience. That is, assuming you have the fish's best interests at heart. I don't mean to sound blunt, but it sounds like you don't have a grasp on basic fish keeping and sometimes, knowing when to throw in the towel is the best solution for both you and for the pet.
My Mbu is three years old and 26" long, by the way, so I'm not just a guy quoting the internet.
Best of luck to you and to the fish.