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Wrasse (family Labridae)

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Humphead (Napoleon) wrasse (Cheilinus undulatus), a large green reef fish with a forehead bulge.

Humphead (Napoleon) wrasse (Cheilinus undulatus), Red Sea.

Image: Diego Delso, CC BY-SA 4.0, via Wikimedia Commons.

Overview

Wrasses (family Labridae) are one of the largest and most colourful families of fish, found mainly on coral reefs and rocky coasts around the world. They range enormously in size — from tiny cleaner wrasses just a few centimetres long to the giant humphead (Napoleon) wrasse (Cheilinus undulatus), shown here, which can grow to around two metres and is one of the biggest reef fish. Wrasses are typically slender, with thick lips and protruding teeth, and many are spectacularly patterned.

Two things make wrasses especially fascinating: many run “cleaning stations” that service other fish, and a great many can change sex during their lives.

Note: the wrasse family is huge and varied; details here draw on the family broadly, with the humphead wrasse as a reference. Treat general statements as approximate and verify against authoritative sources.

Habitat & Range

Wrasses live mostly on tropical and temperate coral reefs, rocky reefs, and seagrass beds worldwide, generally in shallow, sunlit water. Different species fill different niches across the reef, and the humphead wrasse favours steep outer reef slopes and channels in the Indo-Pacific.

Diet

Most wrasses are carnivores, eating invertebrates such as molluscs, crustaceans, sea urchins, and worms, which they crush with strong jaws and throat teeth; larger species take bigger prey. Cleaner wrasses have a special diet of parasites and dead skin picked from other fish. The humphead wrasse is even able to eat hard or toxic prey, including crown-of-thorns starfish that damage reefs.

Behavior

Cleaner wrasses are famous for setting up “cleaning stations,” where larger fish queue up to have parasites and dead tissue removed — a mutually beneficial relationship important to reef health. Equally remarkable, many wrasses are sequential hermaphrodites: they commonly begin life as females and can later change into males (often the largest, most colourful individual becoming a dominant male). Wrasses are active by day and many bury themselves in sand or hide in crevices to sleep at night.

Human Interaction & Conservation

Wrasses are vital to reef ecosystems as cleaners and as controllers of invertebrate pests, and some are popular in the aquarium trade. The giant humphead wrasse, however, is heavily overfished for the live-reef-fish food trade and is assessed as Endangered, making it a flagship for reef conservation. Status varies widely across the family. Consult WoRMS and the IUCN Red List for species-specific status.

More photos of the wrasse

A juvenile humphead wrasse with maze-like facial markings.

Humphead wrasse (Cheilinus undulatus), juvenile.

Image: Bernard DUPONT from FRANCE, CC BY-SA 2.0, via Wikimedia Commons.

Frequently Asked Questions — Wrasse

Can wrasses really change sex?
Yes — many do. A great number of wrasses are sequential hermaphrodites, commonly starting life as females and later changing into males. Often the largest individual in a group becomes a dominant, brightly coloured male. This sex change is a normal and important part of the biology of many wrasse species.
What is a cleaner wrasse?
A cleaner wrasse is a small wrasse that feeds by removing parasites, dead skin, and debris from other fish. They set up 'cleaning stations' on the reef where larger fish — even predators — line up to be cleaned. It's a mutually beneficial partnership: the wrasse gets food, and the client fish gets healthier.
How big do wrasses get?
It varies enormously. Many wrasses are small, just a few centimetres long, but the family also includes the giant humphead (Napoleon) wrasse, which can reach around two metres and is one of the largest reef fish. So 'wrasse' spans everything from tiny cleaners to reef giants.
Why is the humphead wrasse endangered?
The giant humphead wrasse is prized in the live-reef-fish food trade and has been heavily overfished, while also being slow to mature and naturally not very abundant. These pressures have made it Endangered, and it is now a focus of reef conservation. Status for other wrasses varies and should be checked against the IUCN Red List.

Sources and further reading

Authoritative wildlife references used for general educational context. Conservation status should always be verified against current IUCN Red List data. External links open in a new tab.