Naso brevirostris

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Common Name
Spotted Unicornfish
Binomial Name
Naso brevirostris
Naso brevirostris 1.jpg
Scientific Classification
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Perciformes
Family: Acanthuridae
Genus: Naso
Species: brevirostris

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Common Names

  • Spotted Unicornfish



Adults are blue gray to olive brown, and adult males have spotting throughout the body. Juveniles lack the prominent horn from which the species gets its name. This appears when N. brevirostris is ~ 25cm, becoming prominent once the fish reaches ~50cm [1]. Males are generally much larger and have bigger, more prominent caudal peduncles.

Similar Species

This is one of 3 Naso sp. with the horn projecting from its head.

Maximum Size

60cm [2]

Associated Organisms

Anything that lives in symbiosis, parasitic or opportunistically with it.


These are large active fish that can change their colours rapidly when threatened, or as a sign of submission, or when angry.

Captive Care

Tank Size

Since the fish grows to 60 cm and should attain 80% of this growth in the first 15% of its life [1], a very large tank is warranted. Furthermore, the adults are open water swimmers. At the very least an 8-10 x 2.5 x 2.5 would give the fish some room to swim and turn around.

Water Flow





Juveniles feed on various macro algaes and spend their time very close to reef slopes. A Great Barrier Reef study in 1994-6 showed Cladophora as the dominant algae consumed, accounting for ~50% of intake [2]. As they mature N. brevirostris become open water swimmers, sometimes forming large schools to feed on zooplankton.

In captivity juveniles should regularly be offered various macro algae, and adults meaty foods to mimic their natural diet: eg assorted frozen foods and DIY mix.

Growth Rate

As noted earlier, the fish grows rapidly in the early years of its life. Unfortunately stunting can occur in the wrong environment (see Schultz for further reading).


They are vulnerable to the same diseases as other WC fish.


This fish is unsuitable for most home hobbyist tanks in the long run, for reasons discussed earlier.




Small passive fish should be added first. For their size the fish are active but fairly passive.


Naso sp. have been anecdotally reported to eat certain soft corals such as Xenia. This is uncommon and may be diet related


Usually ignores invertebrates / corals.


How it reproduces, how suitable it is to breeding or captive propagation, techniques on how to etc.

Local Ecology


Found extensively throughout the Indo Pacific stretching from the Red Sea down to East Africa, through to Hawaii and southern Japan. It is also found as far south as Lord Howe Island [2].


Most commonly found at 4-46m depth. Steep reef walls and drop offs are preferred.

Additional Information

Some additional notes on it that don't fit in the above sections.



  1. 1.0 1.1 ( Schultz, H., Unicorns: More Than a Myth in Reef Aquariums; The Genus Naso, Reefkeeping Magazine, 4(6), 2005.
  2. 2.0 2.1 2.2 ( Froese, R., Pauly, D. Fish Base, World Wide Web electronic publication, 2008, Retrieved: 10 March 2011.