Orangespine Unicornfish
Naso lituratus
Type: saltwater, reef fish
Physical Characteristics
Oval, compressed body with a smooth, velvety skin typical of the Naso genus. Coloration is greyish-brown to purplish-blue. Distinctive features include a bright yellow mask around the eyes, orange lips, and two pairs of bright orange fixed spines on the caudal peduncle. The dorsal fin is black with a blue line, and the caudal fin is slightly emarginate with yellow edges.
Habitat & Distribution
Found in the Indo-Pacific region, inhabiting coral-rich areas, rocky reefs, and lagoons at depths of 5 to 90 meters.
Size & Weight
Typically reaches lengths of 25 to 35 cm (10-14 inches), with a maximum recorded length of 45 cm (18 inches).
Similar Looking Species
Naso elegans (Blonde Naso Tang), which is very similar but found in the Indian Ocean and features a yellow dorsal fin versus the black dorsal fin of Naso lituratus.
Ecological Role
Primary consumer that helps control algae growth on coral reefs, preventing algae from smothering corals.
Diet
Mainly herbivorous, feeding on leafy brown algae such as Sargassum and Dictyota. It is a grazer that uses its small teeth to rasp algae from rocks.
Behavior
Generally solitary but can be found in small groups or large schools. They are diurnal (active during the day) and spend most of their time foraging along reef slopes.
Reproduction
Pelagic spawners; they release eggs and sperm into the water column. The larvae are planktonic and drift with the currents before settling onto a reef.
Conservation Status
Least Concern (IUCN); population is currently stable.
Identification Tips
Look for the bright orange 'peduncular' spines near the tail and the yellow mask stretching from the eye to the mouth. Unlike other unicornfish, this species does not develop a prominent bony 'horn'.
Interesting Facts
The orange spines on the tail are razor-sharp and are used for defense against predators. Interestingly, despite being in the genus Naso (meaning 'nose'), this specific species only develops a slight bump rather than a long rostrum.
Identified on: 4/18/2026
Mode: Standard