What Is a Unicorn Fish

What Is a Unicorn Fish?

What is a unicorn fish? A fish with a unicorn horn?

Today, we are going to learn all about this magical fish. What does it look like, where does it live, what does it eat and why does it have a horn? We are also going to reveal the secret magical power unicorn fishes have.

What Is a Unicorn Fish?

Actually, unicorn fishes consist of several species. These marine fishes are all part of the Acanthuridae family. All members of the Acanthuridae are not unicorn fishes; unicorn fishes are a genus of this family. The other members of the family are the surgeonfishes and tangs.

The genus of unicorn fishes, also known as Naso, consists of 20 different fish species.

Unicorn fishes are quite large. Members of the largest unicorn fish species, white margin unicornfish, can even grow up to 3.2 ft (100 cm) long!

Unicorn fishes have a pair of very sharp blades on both sides of their tails. The blades are part of their spine. Unicorn fishes use their sharp tail for self-defense. They are very effective for that purpose, as the blades are as sharp as a surgical knife. The male fish can also use their tails for fighting each other, although unicornfish are not aggressive in general.

The name “unicorn fish” comes from the horn-like extension, long spike, on the forehead, which is found on some species of this genus. The horn starts growing when a young unicornfish reaches the length of 5 inches (13 cm).

So, narwhal, the medium-sized whale known as “the unicorn of the sea” is not the only sea unicorn out there. The unicorn fish really is an underwater unicorn!

What Is a Unicorn Fish - Bluespine Unicornfish
A Spotted Unicornfish. Photo by Juan Álvarez Ajamil on Unsplash

Where Do the Unicorn Fishes Live?

The unicorn fishes can be found on the Indo-Pacific from Africa to Hawaii. They live in warm, tropical waters near coral reefs.

What Does the Unicorn Fish Eat?

The unicorn fishes are herbivores. They eat algae from corals. The corals need to get rid of the algae, otherwise, it can kill them. By eating the algae that build up on the corals, the unicorn fishes benefit the ecosystem and help corals to survive.

Unicorn fishes have small mouths and small, sharp teeth. Their teeth are designed for the exact purpose to eat algae from corals without harming the corals.

Plankton can also be part of the unicorn fishes’ diet.

Why Do the Unicorn Fishes Have a Horn?

Biologists are not sure about the purpose of the unicorn fishes’ horns. It is not for self-defense, though; that’s what the unicorn fish has the tail blades for.

The Unicorn Fish Has a Magical Power

Even though the unicorn fish has a horn, it does not look like a unicorn very much. But it has a special power. You could even call it a magical power!

The unicornfish can change their color instantly based on their mood or environment. Even unicorns can’t do that!

Apart from the horn, the unicornfishes share another common trait with unicorns. Just like unicorns, the unicornfishes are known for their speed. The unicornfishes have laterally flattened bodies, which are designed for speed. While they may not swim at the speed of sound, they are very fast.

What Is a Unicorn Fish - White Unicorn Fish

Unicorn Fish – A Unicorn in Its Own Way

The unicorn fish does not look like a unicorn much, apart from the horn on its forehead. But it has a special power, almost like a magical power.

Just like unicorns, the unicorn fishes are known for their speed. Unicorns are vegetarians (at least that is very likely), and so are unicorn fishes.

Unicorn fishes are peaceful, and rarely aggressive, although they have sharp tail blades they can use for defending themselves. Unicorns are known for their peace-loving nature as well, so it seems to me unicorns and unicorn fishes have more in common than you might think!

If you do scuba diving, and you have been lucky enough to see a unicorn fish, please let me know! Do you think the unicornfish is any similar to unicorns? Feel free to share your opinion in the comment section below.

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  1. Hi, Kirsti!

    I have never heard of a unicorn fish, so this was a fun read! I did know about narwhales and their horn, which are almost exactly like a unicorn horn. They are even a spiral horn such as a unicorn has. I have ALWAYS been fascinated with narwhales for this reason. But unicorn fish were unknown to me. They definitely don’t really look like unicorns, but hey, maybe they’re just as magical. Gorgeous too.

    Thanks for the post!

    1. Hi,

      The narwhal tusk definitely looks like a unicorn horn, it’s even spiraled, like you mentioned. But the difference is, that the narwhal tusk is well, a tusk, not a horn. The unicorn fish’s horn, on the other hand, is an actual horn, even though it doesn’t look like a unicorn horn at all. Appearance can deceive, but magic is on the inside, as the unicorn fish proves, I think. ^^ Thanks for sharing your thoughts on the unicorn fish (and narwhal!).