Naso fageni was first formally described in 1954 by the American ichthyologist James Edwin Morrow with its type locality given as Bugsuk Island in the Philippines.

[6] The horseface unicornfish has an oval, laterally compressed body and in the largest specimens there is a short bony protuberance above the mouth.

[7] There are long filaments growing from the tips of the lobes of the caudal fins in largere specimens, and the possession of these may be limited to males.

[6] The overall colour is pale grey to greyish brown with the adults being marked with small dark sopots on their bodies and the juveniles having a white band between the bony plates on the caudal peduncle.

In the western Indian Ocean the horseface unicornfish occurs along the eastern coast of Africa from the Gulf Of Aden to central Mozambique, the Comoros ISlands, Aldabra and the Saya de Malha Bank.