Saltwater parrotfish eat marine algae, sea grasses and coral. Although they are considered to be herbivores, they do not necessarily follow a vegetarian diet. By digesting and excreting coral, parrotfish feeding procedures play a role in the production of ocean sand. A parrotfish can produce 200 pounds of sand in one year, and their feeding is largely responsible for the destruction of many coral reefs.
The parrotfish gets its name from its mouth, which is made of fused teeth and looks similar to a parrot's beak. They use the beak to tear off chunks of coral, which is ground with a second set of teeth in the back of the throat. This process releases algae, providing nutrients to the parrotfish.
Saltwater parrotfish are often confused with blood parrot fish, which are kept as fresh aquarium pets. According to About.com, blood parrots can be fed flake, live, frozen and freeze-dried foods. Bloodworms and live brine shrimp are popular treats for these fish.
About.com recommends feeding blood parrot fish foods that sink, because they are easier for the fish to eat than food that floats. Their vibrant colors can be maintained by feeding them food rich in beta-carotene and canthaxanthin, both vibrant molecules.