The right answer is Damselfish
The damselfish is a species of herbivorous fish that contributes to a balance of marine plants by eating algae among corals, to prevent the proliferation of algae and to promote the growth of coral reefs. The parrotfish (Scaridae) or "coral cleaner" has the same similarity of the diet with the same equilibrium that the damselfish offers, but it can also feed on coral.
