Humphead wrasse

The humphead wrasse, known scientifically as Crassilabrus undulatus, is a massive fish found on coral reefs.

It is the largest living member of the Labridae family, which includes various wrasses and hogfishes. This species is a vital top predator in the Indo-Pacific reef ecosystems. Because it protects the habitat of many other species, it is called an umbrella species. Protecting the humphead wrasse helps ensure the survival of many other creatures that share its range. It is also known by common names like the Māori wrasse or the napoleonfish.

This fish has a very distinct physical appearance that makes it easy to identify. Adult males are typically larger than females and can reach lengths of up to two meters. However, the average length for the species is usually around 1.5 meters. Females are much smaller and rarely grow beyond one meter. You can recognize them by their thick lips and two black lines located behind their eyes. Large adults also develop a prominent hump on their foreheads. Their color varies from olive to vibrant green or purplish-blue, often featuring yellow undulating lines on the head.

As opportunistic predators, humphead wrasses eat a wide variety of marine life.

They consume mollusks, such as gastropods and bivalves, as well as sea urchins and crustaceans. They can even eat toxic animals like sea hares and boxfish. To find prey hiding under the sand, they may eject water to displace the sediment. They also use their noses to search the ground for food. To eat a hard sea urchin, the fish carries it to a rock. It then strikes the urchin against the rock using brisk, sideways head movements.

The biology of the humphead wrasse is quite unique. They are protogynous hermaphrodites, meaning they can change their sex during their lives. Some individuals begin as females and transition into males around nine years of age. They reach sexual maturity between five and seven years old. These fish are long-lived and can survive for approximately 30 years. At certain times of the year, adults gather in local spawning aggregations to reproduce. They release spherical, unpigmented eggs that are only 0.65 mm in diameter.

Scientists have recently updated our understanding of how this fish is classified. For a long time, it was placed in the genus Cheilinus. However, genetic analysis showed it was actually closer to the slingjaw wrasses in the genus Epibulus. Because of this, it was moved to the resurrected genus Crassilabrus in 2025. In 2013, researchers even sequenced its mitogenome to study its genetics. They used a test involving 15 microsatellite loci to study different populations. This helped scientists understand how the species is spread across different geographical areas.

Humans have a significant impact on the survival of this species. The humphead wrasse is highly valued for food and the marine aquarium trade. In Malaysia, it is considered a delicacy and has a high retail value. In the state of Sabah on Borneo Island, the population has declined by roughly 99 percent. This decline is largely due to the live reef food-fish trade. The fish is currently listed as endangered on the IUCN Red List. It is also protected under Appendix II of CITES to regulate its international trade.

Many different countries have implemented laws to prevent the disappearance of the humphead wrasse. For example, Taiwan has strict fines and jail sentences for anyone who hunts them. In Australia, the species has been protected in Queensland since 2003 and Western Australia since 1998. Other places like the Maldives and Niue have instituted export bans. Despite these efforts, illegal and unregulated fishing remains a major challenge. Many fishers continue to participate in the trade because of the high value of the fish. Conservation depends on better monitoring and stronger accountability systems globally.