Marine and freshwater angelfish are omnivores and feed on animals and plants. The ideal diet for marine angelfish varies with species, but most prefer to graze and nibble on algae. Freshwater angelfish eat flakes, vegetables, and frozen and freeze-dried foods, but they prefer live foods.
Saltwater angelfish eat macroscopic algae, diatoms and small crustaceans. Introducing them to an established aquarium with a generous supply of algae and live rock growth helps them to adjust to aquarium foods. Some species of marine angelfish feed exclusively on sponges and may starve in aquariums if their diets don't include frozen edible sponges. Suitable aquarium foods include spirulina, nori, marine flake foods, live brine shrimp and other dried or frozen foods meant for carnivores.