Bluespine Unicornfish

Naso unicornis

Also known as Bluespine Unicorn Tang, Bluespine Surgeonfish, Blue-spined Unicornfish

SaltwaterFish

Bluespine Unicornfish (Naso unicornis) — Rjcastillo · CC BY 4.0

Care at a glance

Temperature: 75–81°F (24–27°C)
pH: 8.1–8.4
Adult size: 23.6 in (60 cm)
Minimum tank: 396 gal (1,500 L)
Temperament: Mostly peaceful
Social behavior: Solitary
Swim level: Middle
Difficulty: Difficult
Breeding: No record
Rarity: Common
Reef safe: Reef safe
Origin: Indo-Pacific from the Red Sea and East Africa to Hawaii, on outer reef slopes and channels with steady current.
Family: Acanthuridae

Overview

This fish outgrows almost every home tank, so plan on 1500 litres or more with wide open swimming room and hold temperature at 24 to 27 C. Keep only one and feed a heavily plant-based diet of nori, macroalgae and spirulina with occasional meaty foods. It ignores corals and most invertebrates, so the limit is space, not reef safety. Treat it as a species for very large custom systems or public aquariums.

In the wild

Bluespine unicornfish graze leafy macroalgae on current-swept outer slopes, often in loose groups. Adults grow a blunt horn on the forehead and two fixed blue blades on each side of the tail. They cover a lot of ground while feeding and are strong swimmers. This is a very large surgeonfish that keeps growing for years.

Good to know

Naso unicornis reaches around 60 cm and occasionally more in the wild. The forehead horn develops with age and does not regenerate if broken. Unlike Acanthurus blades, the paired tail spines of Naso are fixed rather than folding.