Unicorn Tang (Naso unicornis)

The Unicorn Tang (Naso unicornis), also called the Bluespine Unicornfish, is one of the true giants of the surgeonfish family, and this is a juvenile. Right now it is a smooth grey-olive to bluish grazer with fine blue edging on its dorsal and anal fins and two bright blue blade plates at the base of the tail. As it grows it develops a short, blunt horn on its forehead and a powerful, streamlined body built for cruising open water. It is peaceful with most fish, reef safe with corals, and endlessly entertaining. It also grows to around 2 feet, so please read the next section before you take one home. Browse the rest of our saltwater livestock and supplies to plan around it.

Before You Buy

This fish gets very large. Naso unicornis reaches 20 to 24 inches in aquariums and close to 27 inches in the wild, and juveniles grow quickly. Long term it needs a system of 300 gallons or more with 8 feet or more of open swimming length. A juvenile can grow out in a smaller large tank for a limited time, but only if the big tank is a real plan and not a someday. For keepers with that space it is a hardy, personable centerpiece that can live for decades.

Care Guide

• Tank size: 300 gallons or larger long term, with a long footprint and open water in front of the rockwork. Swimming length matters more than height.
• Flow and oxygen: strong water movement, efficient skimming, and good surface agitation. Large tangs use a lot of oxygen.
• Water parameters: 72 to 78°F, pH 8.1 to 8.4, salinity 1.020 to 1.026.
• Feeding: herbivore that prefers leafy brown and red macroalgae. Offer marine seaweed on a clip every day, plus algae-based pellets and occasional meaty frozen food. It will also eat macroalgae growing in the display.
• Parasites: like all tangs it is susceptible to ich when stressed. Quarantine new fish in a separate tank before adding them, feed well, and avoid crowding.
• Handle with care: the blue tail blades are fixed in the open position and sharp. Move it in a container rather than a net, and keep hands clear of the tail.

Specifications

Compatibility

Peaceful toward most unrelated fish, and it grows big enough that very little bothers it. It can be intolerant of other unicornfish and similarly shaped tangs, so if you want more than one Naso, such as our Vlamingii Tang, do it only in a very large system and add them at the same time. Good tank mates for a big system include a Yellow Foxface, the Lamarck Angel, Ruby Anthias, and a school of Blue Green Chromis. Corals and invertebrates are safe, but decorative macroalgae in the display will be eaten.

Recommended Foods & Supplies

• Rod's Food Leafy Purple Seaweed for daily grazing
• Two Little Fishies SeaVeggies Purple Seaweed on a VeggieMag Seaweed Clip
• Vitalis Marine Grazing Pellets, an algae-forward staple
• Ocean Nutrition Frozen Formula Two, a vegetable-rich frozen blend
• Selcon Vitamin Booster to soak foods
• Innovative Marine AccuDrip Acclimator for a slow, low-stress introduction

FAQ

How big does it really get?
Around 20 to 24 inches in a large aquarium, and bigger in the wild. It is one of the largest tangs regularly sold in the hobby.

Can it live in my 125 gallon tank?
Only briefly as a juvenile, and only if a much larger tank is already planned. It grows fast, and a cramped unicornfish becomes stressed and prone to disease.

When does it grow the horn?
The horn starts to appear as the fish approaches adult size, usually once it passes about 6 inches, and stays fairly short and blunt in this species.

Is this the same as the Naso Tang?
No. The fish usually sold as the Naso Tang is a different species that stays smaller and has no horn. The Unicorn Tang is the bigger, horned relative.

Is it reef safe?
Yes with corals and invertebrates. It will graze any macroalgae in the display, so keep chaeto and decorative algae in the sump or refugium.