Naso lopezi was first formally described in 1923 by the Norwegian-born American ichthyologist Albert William Herre with its type locality given as Ambil Island southwest of Manila Bay in the Philippines.

[5] The overall colour is greyish with dense black spotting on the upper body and caudal fin,[6] This species has a maximum published total length of 60 cm (24 in).

[1][6] The elongate unicornfish is typically found in areas of the outer reef slopes where there is a strong current, usually at depths greater than 6 m (20 ft).

[5] Naso lopezi feeds largely on ctenophores and crustaceans, they will also eat algae, diatoms, dinoflagellates and molluscs.

These feed in the upper part of the water column in the middle of the day and near the bottom in the early morning and late afternoon.