Unicorn fish

Naso is a genus of marine ray-finned fishes belonging to the family, Acanthuridae, the unicornfishes, surgeonfishes and tangs. The fishes in this genus are known commonly as unicornfishes because of the "rostral protuberance", a hornlike extension of the forehead present in some species. Unicorn fish are popular with spearfishermen and may be cooked by grilling them whole. Unicornfish primarily live around coral reefs and eat mostly algae. It is very popular in Maldives. This genus is distributed across the Indo-Pacific from Africa to Hawaii.

Source: Wikipedia