naso

Naso is a genus of marine fishes in the family Acanthuridae, commonly known as unicornfishes. Members of this genus typically have a laterally compressed body, a small mouth adapted for grazing algae, and in some species a horn-like protuberance on the snout. Like other surgeonfishes, naso species possess one or more sharp, blade-like spines on the caudal peduncle that can be used for defense.

They are native to the Indo-Pacific region, with ranges extending from the Red Sea and eastern Africa to parts of the central and western Pacific. Naso fishes inhabit coral reefs, reef slopes, and lagoons, usually at shallow depths up to about 40–50 meters. They are commonly seen in schools, especially when young, and feed mainly on macroalgae, epilithic algae, and biofilm on hard surfaces.

Taxonomy and species within the genus Naso are organized as a group of relatively large herbivorous reef fishes. The genus comprises around a dozen recognized species, varying in size from modest to quite large depending on the species. Adults typically have a robust body shape and may attain substantial lengths. Reproduction occurs through broadcast spawning, with eggs and larvae that are pelagic and dispersed by ocean currents.

Human interactions with Naso species include their occasional collection for marine aquariums, though their large size and specific dietary needs limit suitability for many hobbyists. They are also subject to fisheries pressures in some regions and can be affected by reef degradation and habitat loss, which influence local populations.