Food can really all depend on the fish that you have.
All malawi cichlids I found love New life spectrum cichlid formula, and I have found that to be the best food out there for them, brings out great color in them and I never never seen them eat food with such verosity as this. With all my fish this was their main diet.
For peococks I would supplement a couple times a month with krill and mysis shrimp.
For haps they would get krill, shrimp, and cut up pieces of smelt.
For Mbunas, they would get a flake with a high spirulina content. I would also give them romane lettuce, cucumber, and peas with out the skins. For the cucumber, I would just cut a chunck, take the skin off, wash it and stick it on a fork so it would sink. For the peas, just lightly boil them, enough to get the skin off.