Marine life identification guide > Surgeonfish & unicornfish

Surgeonfish & unicornfish species identification guide

A peaceful herbivorous fish, hiding a redoubtable scalpel-like spine

Acanthuridae (a family comprising surgeonfish -or tangs- and unicornfish) have in common scalpel-like thin sharp blades located at the base of their tail. In case of danger, they draw those blades and use their tail to defend themselves.

Though middle-sized (15 to 40 cm at most), they are some of the most colorful reef fish. They mostly feed on algae and play a crucial part in the reef ecosystem as they leave room for coral to grow.

School of convict tang
The convict tang is frequently seen shoaling in the shallow lagoons of the Indo-Pacific. Here, encountered in Lagon de Trou d’Eau, Reunion Island.

Surgeonfish can be observed alone, in small groups, and sometimes in impressive schools of hundreds of fish.

Where are surgeonfish found?

The most famous surgeonfish undoubtedly is the palette surgeonfish (or blue tang). Kids and grown-ups know it as Dory, the unforgettable yet forgetful sidekick in Pixar’s “Finding Nemo”. The best places to spot palette surgeonfish while snorkeling are the Western Indian Ocean (Zanzibar, Coromos, Madagascar and Seychelles) and the Great Barrier Reef.

Palette surgeonfish
The palette surgeonfish, aka Dory, has become one of the most iconic reef fish. Here, spotted in Anse Patate, Seychelles.

You’re most likely to spot the convict surgeonfish with its black vertical stripes, very common from Eastern Africa to the Pacific area. In Hawaii, the yellow tang is unmissable, while the razor surgeonfish can be easily spotted in the eastern Pacific, including the Galápagos Islands.

Only 3 surgeonfish species live in the Caribbean, including the Atlantic blue tang that can be seen at most spots.

Caribbean & Western Atlantic surgeonfish

Indian & Pacific Oceans surgeonfish

Eastern Pacific Ocean surgeonfish

Discover more fish families

Butterflyfish & bannerfish

Sergeant major




Marine life ID guide

See all fish families

Still trying to identify a fish you've seen?
Ask our experts!

    Our underwater life experts are here to help you identify a species you've seen. Please specify where you saw this species and, if possible, attach a photo

    You can upload pictures in .jpg, .png and .bmp format. Files in .JPG (capital letters) can't be uploaded with this form. Please modify the file extension with .jpg before uploading.

    Check out our selection of fish identification guides!

    Fish ID
    Fish ID book on the beach

    Want to learn more about the species you’ve observed or photographed underwater?

    The identification guides are true treasures for those curious to know about the underwater world, and a beautiful way to dream about your future snorkeling explorations!