They can be any of the three! Parrotfish, butterflyfish, surgeonfish, blennies, and damselfish are examples of herbivorous fish. You can find these animals in shallow water where sunlight can penetrate, allowing plants to photosynthesize. Glassweed, latok, Halimeda, and Sargassum are among the seaweeds they consume. They also consume corals like Turbinaria. Corals aren't plants, but the fish aren't aware of this. Mullets feed on small aquatic animals when they are young and switch to seaweed once they reach maturity. Almost all freshwater fish are omnivores. It means they eat plant and animal material, including algae and parasites from other fish. Bonnethead sharks are also omnivorous, the only sharks known to be so. Aside from the bonnethead, predatory fish, such as tuna and sharks, may consume a plant that is useless to them. They have evolved to consume and enjoy meat.