Hi bro,
For diet, If you are talking abt Pomacanthus, you can feed various diet, flake contain veggie, Mysis soak with additive, and sea weed. For angel like Holacanthus, apolemichthys and Chaetodonplus and Regal, you need to give them additional sponge meal. Not all fish love the Angel fomula sponge, you need to train and let them adapt to the diet you provide.
The feeding table can be plan
AM: Sponge and seaweed
PM: Mysis soak with selcon and vitamin
Evening: Pellet and Flakes.