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Related Articles: Naso lituratus, Surgeon Family, Acanthuridae, Ctenochaetus, Paracanthurus, Zebrasoma

/The Conscientious Marine Aquarist

Unicorn Tangs, The Genus Naso, Family Acanthuridae, Part 1 of 3

To: Part 2, Part 3

By Bob Fenner

Naso unicornis

Surgeonfishes: Tangs for  Marine Aquariums
Diversity, Selection & Care
New eBook on Amazon: Available here

New Print Book on Create Space: Available here
by Robert (Bob) Fenner

Just how many unicorn or Naso tangs are there? Most everyone knows the Naso, or lipstick surgeon, Naso lituratus, but there are at least sixteen other species. All these "Naso" tangs share the traits of being open, active swimmers, surgeonfish "spines", and a propensity for getting BIG.

Unicornfishes are unlike other tang genera in their space requirements, temperament and food needs. Here are my ideas of what makes a good specimen, how to go about selecting them, and notes on successful maintenance of Nasos in captivity.


The family of surgeon, Doctorfishes or tangs, Acanthuridae ("Ah-kan-thur-id-ee") is of immense use to the saltwater aquarium hobby. Of the six genera and seventy two described species, some are indeed "standards". How many can you name? The three species of blue tangs, Bristlemouths of the genus Ctenochaetus, the pelagic Prionurus, the mundane yellow tang and other Zebrasoma, the many Acanthurus (powder brown & blue, Achilles, gold rim, orange-shoulder, sohal, mimic, clown...). The Acanthurids are an essential marine aquarium family.

The sub-family Nasinae, of one genus (Naso) and about seventeen species are the Unicornfishes. They may be externally distinguished from all other surgeonfishes by their possession of two anal spines (versus three), and three soft pelvic rays (rather than five). Like all surgeons, those of the genus Naso sport sharp spiny processes (one or two) on their caudal peduncles; a formidable weapon.

Genus Naso ("Nay-zoh") for the most part is unknown to hobbyists with the exception of N. lituratus. Though this celebrated species is the acknowledged "pick of the litter" in color and markings, there are some other worthwhile Nasos.

Unicornfishes come in slender, tubular shapes, as well as more typical flattened "Acanthurus" form; with or without "horns", all Naso species have similar care. Here we'll expand only on the five that are principally available in the hobby worldwide.

Naso annulatus (Quoy & Gaimard 1825), the Whitemargin Unicornfish. Indo-Pacific; East Africa to Hawai'i. To a meter in length. This eight inch one off of Heron Island, Australia's Great Barrier Reef.  http://fishbase.org/Summary/species Summary.php?ID=6019&genusname= Naso&speciesname=annulatus

Naso brachycentron (Valenciennes 1835), the Humpback Unicornfish. Indo-Pacific; eastern Africa to the Marquesan and Society Islands. To thirty six inches in length... yes a yard long. Off of Gili Air, Lombok, Indonesia and N. Sulawesi.  http://fishbase.org/Summary/species Summary.php?ID=6020&genusname= Naso&speciesname=brachycentron

Naso brevirostris (Valenciennes 1835),  sometimes called the Shortnose Unicorn Tang, is mis-named both scientifically and colloquially; it has a long nose as an adult. There are Naso species with much shorter, even absent the "horn" on the head. This grayish-green bodied fish is occasionally imported from Hawaii and the Indo-Pacific. To two feet long. Fr. Polynesia and Fiji pix. http://fishbase.org/Summary/species Summary.php?ID=6021&genusname= Naso&speciesname=brevirostris

Naso caesius Randall & Bell 1992, the Gray Unicornfish. To about two feet in length. Pacific Ocean; Marianas, Marshalls, Hawai'i, Noumea. Here off of Hawaii's Big Island at a shallow water cleaning station, generally much deeper. 

Naso elegans the Indian Ocean (and Red Sea) Orange-spined Unicornfish. To 45 cm.; similar to N. lituratus but found in I.O. and RS. Also similar feeding (on macroalgae). Mauritius 2016.

Bigger PIX:
The images in this table are linked to large (desktop size) copies. Click on "framed" images to go to the larger size.

Naso hexacanthus (Bleeker 1855), Sleek Unicornfish. Indo-Pacific species... to about 30 inches in length. Not kept in home aquariums... as are other too-large Naso species from these islands. Neither males nor females develop a horn; but do have black tongues! One in Hawaii, a flashing male in the Red Sea shown below. This species has a dark margin on its preopercle and operculum that helps distinguish it from similar species. 

Naso lituratus, the Naso Tang to most aquarists; it is also known as the tricolor or lipstick tang. There are some who claim that "blonde" and "streamer" versions are different species; they're all Naso lituratus. To eighteen inches in the wild. Below, a Naso in an aquarium, he business end of a Naso in Hawai'i, and a beautiful "streamer" (male) there getting cleaned by a Cleaner Wrasse.  Link to Bigger Pix http://fishbase.org/Summary/speciesSummary.php? ID=1264&genusname=Naso&speciesname=lituratus

Naso lopezi Herre 1927, the Elongate Unicornfish. Western Pacific; N. Japan to the GBR, Similans, Guam, Tonga. To 57 cm. Here is a juvenile in captivity and an adult in S. Sulawesi. http://fishbase.sinica.edu.tw/Summary/species Summary.php?ID=6022&genusname= Naso&speciesname=lopezi

To: Part 2, Part 3

Surgeonfishes: Tangs for  Marine Aquariums
Diversity, Selection & Care
New eBook on Amazon: Available here

New Print Book on Create Space: Available here
by Robert (Bob) Fenner
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