---
title: Bluespine Unicornfish (Naso unicornis)
scientific_name: Naso unicornis
common_name: Bluespine Unicornfish
taxon: Unicornfishes
conservation_status: LC - Least Concern
published: 2024-11-23T22:39:06.575Z
updated: 2026-08-13T21:24:54.560Z
tags: Bluespine Unicornfish, Naso unicornis, Unicornfishes, Red Sea, Marine Life, Diving
url: https://redseacreatures.com/taxon/fishes/bony-fishes/unicornfishes/bluespine-unicornfish
---

# Bluespine Unicornfish (*Naso unicornis*)

## Quick facts

- **Group:** Unicornfishes (*Nasinae*)
- **Size:** up to 70 cm
- **Depth:** 1-80 m
- **Max age:** 55 yrs
- **Diet:** Herbivore
- **Activity:** Diurnal
- **Rarity:** Common
- **Habitat:** Reef edges and surge zones with heavy algal growth
- **Reproduction:** Broadcast spawner, Gonochoric
- **Hazard:** Dangerous, Poisonous
- **Conservation status:** LC - Least Concern

## How to recognise it

- blunt horn projecting from the forehead in adults
- two bright blue fixed blades on each side of the tail base
- olive-gray body, tail with long trailing filaments in males
- length up to 70 cm

A heavy olive surgeonfish with a horn on its forehead and a pair of bright blue blades on each side of the tail base. Seventy centimeters (28 in), and the largest of the unicornfishes here.

The blades are not spines that fold away, as in the true surgeonfishes - they are fixed, permanently erect, and edged like scalpels. The fish uses them by swimming past an opponent and flicking its tail sideways, and the same movement in a net or a pair of hands opens a hand to the bone. That is the entire reason for the flag on this card.

The horn is stranger and less understood. It grows with age, it is present in both sexes, it is not used as a weapon, and no convincing explanation exists for it beyond signaling. Young fish have no horn at all.

It grazes leathery brown algae in surge zones where few other herbivores work, which makes it one of the reef's more important lawnmowers. It is heavily speared across its range and large fish in some regions carry ciguatoxins.

## Also known as

- **English:** Blue-spine nosefish, bluespine unicornfish, Blue-spine unicornfish
- **French:** Nason à Eperons Bleus, Nason à éperons bleus, Nason Vert
- **Spanish:** Barbero de Aguijón Azul, Berbero de Aguijon Azul
- **Portuguese:** Rufia Espigão Azul
- **Swedish:** Noshörningsfisk
- **Japanese:** テングハギ, Tenguhagi
- **Russian:** однорогая рыба носорог, Рыба-единорог
- **DA:** Blåpigget Næsehornsfisk
- **MSA:** Debam

## Scientific synonyms

- *Acanthurus unicornis* (Forsskål, 1775)
- *Chaetodon unicornis* Forsskål, 1775
- *Naso unicornus* (Forsskål, 1775)

## Range

Comoros, Federal Republic of Somalia, Indian Ocean, Kenya, Madagascar, Mozambique, Red Sea, Seychelles, South Africa, Tanzania, Western Indian Ocean

---

*Source: [Red Sea Creatures](https://redseacreatures.com/taxon/fishes/bony-fishes/unicornfishes/bluespine-unicornfish)*
*Updated: August 13, 2026*