Plant-eating fish
Fish that eat algae and plants, such as parrotfish, surgeonfish and grass carp, which keep reefs and ponds clear.
Also: herbivore, grazer
Herbivorous fish graze on algae and water plants. On coral reefs, parrotfish, surgeonfish and rabbitfish crop seaweed that would otherwise smother young corals, and parrotfish grind coral rock with their beaks and pharyngeal teeth, passing it as sand; much of the white sand on tropical beaches comes this way. In fresh water, the grass carp eats water weeds so heavily that it is stocked to clear canals and lakes, and in Indian composite fish culture it is fed on cut grass and plant waste.