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7 Fish with Horns

When most people hear the word “horn,” they think of animals that live on land. However, some animals that live in the water may also have features that look like horns. Unicorn fishes, which are in the genus Naso, are one of the most well-known fish with horns. But not all species in this genus have these bony structures like a unicorn as some of them might only have a small bump, while others might not have this at all. 

7 Fish with horns

1. Bluespine Unicorn Tang 

Bluespine unicorn tang
Bluespine unicorn tang | image by Brian Gratwicke via Flickr | CC BY 2.0

Scientific Name: Naso unicornis

In the Indo-Pacific region, you can find a wide range of interesting fish species, each of which looks different. One such captivating fish is the bluespine unicorn tang, which is also sometimes sold in the aquarium trade.

The creature’s body is bluish-gray, and you can’t help but notice that there are two blue spines on each side of the base of the tail. Also, the creature’s forehead has a large bony horn, making it look unique among other fish. This horn only appears on big fish, and adults can grow to be as long as 70 cm. 

2. Moorish Idol 

Moorish Idol
Moorish Idol | image by Rickard Zerpe via Flickr | CC BY 2.0

Scientific Name: Zanclus cornutus

The Moorish idol is a species of marine fish that you can find in the waters of the Indo-Pacific region. They are easily identifiable by their bold black and yellow colors, and long, trailing dorsal spine. They have small, boney, horn-like projections above their eyes, especially the males. Moorish idols exhibit a unique appearance with their flattened, disc-like body and tubular snout.

Coral reefs, rocky areas, and reef flats are typical habitats for these fish, usually at depths ranging from 3 to 182 meters. The majority of the diet for this species consists of sponges, coral polyps, and various other invertebrates that live in the deeper parts of their natural habitats. 

3. Whitemargin Unicornfish 

Whitemargin unicornfish
Whitemargin unicornfish | image by Brian Gratwicke via Flickr | CC BY 2.0

Scientific Name: Naso annulatus

The whitemargin unicornfish, which you may also know as the ringtailed unicornfish or the short-horned unicornfish, is a large tropical fish that lives in the Indo-Pacific region. This particular species can grow up to 100 cm long, making it one of the biggest in its family.

One of the strangest things about this creature is that it has a bony protrusion in front of its eyes that looks like a horn. These fish like to live in lagoons with shallow, clear water where they eat green algae. But as they grow and become adults, their eating habits change, and they start eating soft zooplankton. 

4. Longhorn Cowfish

Longhorn cowfish
Longhorn cowfish | image by Drow_male via Flickr | CC BY-SA 2.0

Scientific Name: Lactoria cornuta

The longhorn cowfish is another species that possess an easily recognizable characteristic: a pair of long horns that protrude from its head, closely resembling the horns of a cow or bull. These fish inhabit the Indo-Pacific region and can reach lengths of up to 50 cm.

You can find this marine creature in various habitats, such as coral reefs, lagoons, flats, and estuaries, where they actively engage in maintaining the health and balance of the reef ecosystem by preying on invertebrates that pose a threat to the coral reefs. 

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The horns of these fish serve multiple important functions. In the face of danger, these animals can use their horns as a weapon, charging fearlessly at potential predators that dare threaten them.

5. Humpback Unicornfish

Humpback unicornfish
Humpback unicornfish (female) | image by Rickard Zerpe via Flickr | CC BY 2.0

Scientific Name: Naso brachycentron

The humpback unicornfish, also belonging to the genus Naso, is one of the species you can find in the Indian and western Pacific Oceans. Males often have a bony protrusion that sticks out in front of their eyes and sometimes even goes past their mouths.

However, the females lack these characteristics, and it may appear only as a small bump. These creatures can reach a maximum length of 90 cm, and their upper bodies and heads are gray, while their lower bodies are yellowish or whitish.

6. Fourhorn sculpin

Scientific Name: Myoxocephalus quadricornis

The fourhorn sculpin is a ray-finned fish that you can find in marine, brackish, and freshwater habitats across the Holarctic region. The creature displays a head that’s larger than its body with four distinct bony structures, although these particular features aren’t present in freshwater variations of the species.

In marine habitats, the average length that it reaches is between 20 to 30 cm. However, their average length is only around 15 cm for those residing in lakes. They typically feed on invertebrates, small fishes, and fish eggs. 

7. Shorthorned unicornfish

Shorthorned unicornfish
Shorthorned unicornfish | image by Derek Keats via Flickr | CC BY 2.0

Scientific Name: Naso brevirostris

The shorthorned unicornfish is another unusual-looking fish in the Indian and Pacific Oceans. You may recognize them by their short snout, with adults having distinct bony protuberances in front of their eyes, and a coloration ranging from blueish-gray to olive-brown. This unicornfish lives in lagoons and seaward reefs at depths of up to 46 meters, and this species feeds on algae as juveniles and gelatinous zooplankton as adults.