Small fish, mollies, guppies, tetras, earthworms are ok too. Also you can try some frozen krill, bloodworms, mysis shrimp.
Hope you have a really big tank
basically anything that can fit in its mouth, I had one wipe out an entire school of Scissor tail Rasboras (5) in 2 days. When it finished with all the small fish, I started feeding Krill and Blood worm, and he loved them.
my African Brown takes anything from flake to frozen and betta pellets, It sees me coming with the turkey baster and all my clown loaches and knife come to the top to feed from the baster, It's kinda goofy really