Spotted Unicornfish Care Guide
Naso brevirostris is an Indo-Pacific unicornfish with a long forehead horn; juveniles graze algae while adults feed on zooplankton, reaching about 60 cm.
Compiled by Aquairi from published sources · Published · Updated
Overview
Naso brevirostris, the spotted unicornfish of the family Acanthuridae, has a very short, nearly vertical snout and a long, tapering, horn-like projection extending forward from the front of the eyes. Body colour ranges from light bluish-grey to olive-brown with dark grey lines and spots. FishBase records a maximum total length of 60 cm and a maximum age of 25 years.
Taxonomy
- Family: Acanthuridae
- Genus: Naso
- Scientific name: Naso brevirostris
- Described by: Cuvier, 1829
Habitat
The species is marine and reef-associated across the Indo-Pacific, from the Red Sea and East Africa to the Hawaiian, Marquesas and Ducie islands, north to southern Japan and south to Lord Howe Island, with records from the Galapagos. It occupies steep outer lagoon and seaward reef drop-offs, with FishBase recording depths of 0-122 m, usually 4-46 m.
Tank requirements
- Minimum tank volume: 1500 L (396 gal)
- Temperature: 24-26 °C (75-79 °F)
- pH: 8.1-8.4
- Specific gravity: 1.024-1.026
- Carbonate hardness: 8-12 dKH
- Strong water flow
- Lifespan: 10-25 years
Diet
According to FishBase, juveniles and subadults feed on benthic algae, while adults feed mainly on gelatinous zooplankton. In aquaria it benefits from both marine algae and meaty planktonic foods offered multiple times daily.
Compatibility
A semi-aggressive, diurnal mid-water swimmer that forms spawning aggregations and reaches maturity around 25 cm. It needs ample open swimming space. Wrasses, clownfish, angelfish and sturdy triggerfish make suitable tankmates, while other tangs of similar shape should be avoided in smaller systems.
Reef compatibility
The species does not eat coral and is considered reef-safe, though its large size demands a very spacious reef. Maintain carbonate hardness of 8-12 dKH and specific gravity of 1.024-1.026.
Conservation status
IUCN Red List: Least Concern, assessed in 2010 via FishBase.
Spotted Unicornfish (Naso brevirostris) Breeding Guide
Overview
The spotted unicornfish, Naso brevirostris, is a large surgeonfish of the family Acanthuridae ranging across the Indian and Pacific Oceans, from the Red Sea to the Hawaiian Islands and the Galápagos, on lagoon and seaward reefs down to about 46 m. It reaches around 60 cm and matures at roughly 25 cm in length. As a free-spawning reef fish it releases pelagic eggs into open water, which is why it is not reproduced in home aquaria.
Sexing
Males can be distinguished by larger keels on the caudal peduncle than females. There is otherwise no reliable external sexing method useful for a controlled pairing in captivity, and adults are too large to manipulate in home-aquarium conditions.
Spawning Behavior & Trigger
Naso brevirostris forms spawning aggregations and pairs to spawn, releasing eggs and sperm into the water column for external fertilisation. These open-water aggregations, driven by natural reef and lunar cycles, cannot be reproduced inside an aquarium.
Egg & Fry Care
Fertilised eggs are pelagic and develop into the transparent open-ocean larva typical of surgeonfishes, the acronurus, which can remain in the water column for up to about 90 days before settling on the reef. This prolonged planktonic phase, with its need for specialised micro-prey, is the central obstacle to rearing the species without dedicated hatchery technology.
Common Challenges
Captive reproduction of unicornfishes is not a documented home achievement. The combination of a pelagic spawning mode, an extremely long larval drift period and the adult's very large size confines any breeding attempt to research-scale marine aquaculture rather than the home aquarium.