I noticed very quickly that my choc, and I've since found out I'm not alone here, spends a lot of time looking up at the surface. There's a clue there to what they're looking for......fallen insects!
So I bought a tub of small crickets for it to try. It absolutely loves them, so once in a while when I go down for dog food to my local pets at home I'll buy a tub of crickets too. Mine also loves worms from my worm heap, which it'll take from my hand. But they're just treats.
It's staple diet is NLS and Hikari sinking and floating pellets. Small algae wafers too. It'll also gulp in surface flake meant for my smaller fish.
In short, it's not picky at all, certainly not a difficult fish to feed.