My 10 bettas eat frozen brine shrimp, daphnia, bloodworms, a flake food mixed with little shrimps, peas, ants (in season), flies (when I can catch them), blackened sirloin with portabella mushroom glaze, port wine, caviar (courtesy of my rasboras), etc...
The good thing is that the other fish will eat this too. Watching the rasboras devour peas was kind of funny.
I hope you realize I'm joking about the steak and wine.