Unicorn Tang

Unicorn Tang – Also Known as the Unicorn Fish

6 min read

Unicorn Tangs are wonderful fish for a large tank, around 360 gallons or more.

The unicorn tang is also called the blue spine tang and unicorn fish come in a range of colors from blue-green to olive. It usually has a blue edge on its dorsal fins and two bright blue dots near its tail. They are identified by the horn between their eyes.

The unicorn tang usually begins to develop their horn around 6 inches at the back of their head and it doesn’t go past their nose. Their horn is peduncle spines that are always extended and known for getting tangled in things like a net, so please be careful when handling them!

Unicorn Tang

The horn of the Bluespine Unicorn Tang develops when the fish reaches a size of approximately 6 inches. It is located far back on the head and does not extend farther than the tip of the snout. It has large, permanently erect peduncle spines which can easily be tangled in a net or cause injury to the handler.

Pro Tip: Males can be identified by their tail streamers

Our unicorn tang is big and beautiful, with a unique appearance, so it is a great conversation starter for when people come to visit because you can’t help but notice it.

Unicorn Tang Fun Facts For Your Conversation

  • Although blue-green or olive green in the open water, the unicorn tang will actually change the shade of their color in the aquarium to better match your substrate since they are bottom dwellers. Anytime a fish changes its color is for camouflage to protect itself.
  • Eaten raw, boiled, baked, or sauteed, especially in Hawaii due to their abundance.
  • Hawaiian history records the skin of the unicorn tang being stretched over a half coconut shell to make small knee drums.
  • The blue tang grows to over two feet and it is one of the largest fish sold in the aquarium industry.
  • Only fish in its scientific family to grow a horn.
  • Male unicorn tangs can change the color of their horn to warn other males and to let females know that they are interested if you know what I mean.
  • All unicorn tangs have sharp spines near the end of their tail for protection.

At Home

Ours was shy when we first brought it home but it doesn’t take long before it was going everywhere in the tank.

Once it becomes accustomed to you, you can even teach it to take food from your hand or even touch it a tiny bit.

These fish are inexpensive for a large tank, so you won’t regret it!


Origin: Red Sea, Indo- Pacific Region, and Eastern Pacific. Indonesia, Maldives, Philippines, Sri Lanka, Tonga.

Care Level: Moderate

Size: 28 Inches

Attitude: A little aggressive – not much.

Colors: Blue – Green

Diet: Plants – Herbivore

Although tangs eat mainly veggies like seaweed and algae, they will also eat meat sometimes but are perfectly fine on a veggie diet. You can tie the seaweed to something in the aquarium although we recommend a veggie clip and not any fishing line or anything you would tie so they don’t get their horn caught in it.

They mainly eat green and red algae that have coarse leafy blades.

They should be fed 3 times per week.

Ocean Nutrition is a good choice.

Mainly veggies will keep their immune system strong.

Water: 79-82°F, alkaline – pH 8.1-8.3, SG 1.021-1.024

It is important for the water to be well-oxygenated. If there is not enough oxygen in the water, your unicorn tang will sink to the bottom of the tank on their side and appear to be taking in deep breaths.

It is also recommended to have at least 360 gallons of water because unicorn tangs are large fish and need plenty of space to swim around and explore. They also need places to hide because they are just a little aggressive towards other unicorn tangs but very peaceful with other fish.

Unicorn Tang Wild Habitat

Young juvenile unicorn tangs stay closer to the shore although all unicorn tangs stay between the shore and where the deep water begins.

Adult unicorn tang will venture further out even into strong waves but tend to not go past where the deep water starts.


Unicorn tangs are mellow for the most part so they are great for a community tank, although they have been known to be aggressive towards other unicorn tangs or tangs in general.

They also don’t get along with very aggressive fish, especially ones that will swallow them whole!

It is much easier to just have one unicorn fish because of its size. You already need a 360-gallon tank for one so it would have to be even bigger if you start getting more fish.

Aquarium Care

  • The biggest challenge in caring for the unicorn tang is the size of the tank at 360 gallons. They average about 4.5 inches of growth per year so it is pointless to have them in a smaller tank when they are younger.
  • They need the 360 gallons to move around and explore.
  • They can mainly eat an algae-based diet with a tiny bit of meaty foods but they are just fine on algae alone.
  • You will need good filtration, a protein skimmer, and regular water changes to prevent illness from dirty water.
  • Unicorn tangs like a good water current rather than slow water. It will help to get a filter or water pump with adjustable speed.
  • You should have at least a medium-strength light to grow algae which your unicorn tang will happily eat! At least you won’t have to worry about cleaning algae!
  • It helps to have some neon gobies or cleaner shrimp to keep parasites off of your unicorn tang.
  • Keep a lid, they will actually try to jump out of the water.

Unicorn Tang Diet

You can feed your unicorn tang tons of algae-based foods, especially with spirulina.

Use a vegetable clip to place seaweed on the side of the aquarium.

Feed them frozen brine shrimp, mysis shrimp, mosquito larvae, grindal worms, and tubifex worms but remember meat should be no more than 10 percent of their diet.

Unicorn tangs like live rocks with algae growth because they can scrape it off with their teeth, much like they do in the wild.

Pro Tip: You can hang algae sheets with tvegetable clips.

It is better to feed them smaller amounts three times per day instead of a large amount once a day. Feeding them smaller amounts multiple times a day will be easier to keep the water clean.

It is recommended to give your unicorn tang vitamins, especially vitamin C which can reduce certain illnesses. Garlic also helps specifically with marine ich which is common in marine aquariums.

You can soak their food in liquid vitamins or add liquid vitamins to the water.

Unicorn Tang

Frequently Asked Unicorn Tang Questions

How Big Do Unicorn Tang Get?

Unicorn tangs can reach a maximum size of 27-28 inches which is the main problem of keeping them in an aquarium since they are very mellow, hardy fish.

How Fast Do Unicorn Tangs Grow?

Unicorn tangs grow about 4.4 inches per year. They grow 80 percent of their length in the first 4-5 years. It is very hard to keep them in a smaller tank when they are young because of their growth rate

How Much Does a Unicorn Tang Cost?

Unicorn tangs cost anywhere from $80-200 for a normal young aquarium unicorn tang but they can fetch upwards of $800 dollars for a full-size grown unicorn tang.

Is Unicorn Tang Reef Safe?

Unicorn tangs thrive with reefs. They will even eat algae that grow on the reef. Unicorn tang may even change their colors to blend in more with the reef.


Unicorn tang are probably for someone into high-end aquariums considering the size of the aquarium that they need. I would leave these fish alone unless you have the money to furnish such a large aquarium.

In addition to the tank, the unicorn tang itself is expensive, the filtration system will need to filter a lot of water. The big tank will take up space and you will need a solid floor to support a 360-gallon tank.

Also, a 27-inch fish is going to eat a lot more fish food than a 2-inch betta fish.

I guess you could call them the Saint Bernard of aquarium fish. Everything associated with them is bigger, so be careful.

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