I would try a mix of foods and see what it takes to. You can try flakes and pellets, but no telling if it will get used to them, but it will make your life easier when it gets big if it dose get used to them. You can try very small feeders, blood worms, small live shrimp, and even try cutting up small peices of earthworms. All of this will work, but it will be good if you can get it used to eating a variety of things, this way when it get big you will have a variety of choices of food to feed it.