Horse-face unicornfish

This species is widely distributed across the tropical waters of the Indo-West Pacific, ranging from the eastern coasts of Africa (including Kenya and Tanzania) to the Philippines, and north to southern Japan. It primarily inhabits deep outer reef slopes, coastal rocky reefs, and current-swept channels at depths between 3 and 40 meters, often observed swimming in open waters above coral structures.

Belonging to the family Acanthuridae and the genus Naso, Naso fageni is characterized by a unique horse-like head profile with an elongated snout and a straight or slightly concave forehead. It does not develop a protruding bony horn. Adults can reach an impressive size of 60-80 centimeters. It features two sharp, fixed plates (scalpels) on each side of the caudal peduncle.

An active, schooling species that forms small groups or large mobile shoals in the wild to forage along reef slopes. In the aquarium, it requires massive amounts of open water to swim. It is generally peaceful toward smaller, non-related tankmates but can exhibit territorial behavior toward conspecifics or other Naso species.

The base body color is a uniform grayish-brown to light olive-green, fading to pale white on the belly. It lacks the complex color patterns of other Naso species. Mature males develop very long caudal filaments on the tips of their lyre-shaped tail and may have larger caudal plates than females.

Requires a massive marine aquarium of at least 1000-1200 liters due to its large size and active swimming behavior. The aquascape should be minimal and kept to the back and sides to maximize open swimming space. Powerful circulation pumps are required to create strong water movement and maintain high oxygen levels.

Primarily herbivorous, feeding on benthic macroalgae. In captivity, it must be fed multiple times per day with dried nori sheets, spirulina, and high-quality vegetable-based flakes or pellets. Supplement occasionally with frozen foods like mysis and krill to support its high metabolic rate and prevent weight loss.

Demands pristine and stable water parameters: temperature between 24°C and 26°C, pH from 8.1 to 8.4, specific gravity (SG) from 1.020 to 1.025, and carbonate hardness (KH) of 8 to 12 dKH. Strong surface agitation is essential to maintain high oxygenation. A heavy-duty protein skimmer is mandatory to handle waste.

Peaceful toward smaller reef fish and completely reef safe regarding corals. However, large specimens can easily knock over unsecured rockwork or corals when swimming quickly. It houses well with other non-aggressive tangs, angelfish, and wrasses. Avoid keeping more than one specimen of this species per tank.

Captive breeding in home aquariums is not documented and is considered impossible due to the immense swimming space required for their pelagic spawning rituals. In nature, pairs rise rapidly toward the surface at dusk to release gametes into the water column. The pelagic eggs hatch into delicate larvae that drift with ocean currents.

Prone to Head and Lateral Line Erosion (HLLE) if fed an inadequate diet or exposed to poor water conditions. It is also highly susceptible to external marine parasites like Cryptocaryon irritans (marine ich). A strict quarantine process and the use of a UV sterilizer in the filtration system are highly advised.