Do a search, you can feed them human foods, if your fish is omnivorous (meat and vegtables) you can make food for him, outta gelatin, beef heart, squid, shrimp, and some veggies, like cucumber, lettuce, peas etc. puree it all up and add the unflavored gelatin to make a kinda paste, then spread it really thin on wax paper, and freeze it, then you can break little pieces off for him to eat. Its good to feed a variety of different foods.
For instance I feed my tank Flake, shrimp pellets, krill, brine shrimp, blood worms, algae wafers, feeder guppies and homeade food.