Cheilinus undulates belongs to the order of Perciformes and family of Labridae (Wrasses).
This species develops thick lips and a bulbous hump on the forehead. Its body colour can vary between a dull blue-green to more vibrant greens and purplish-blues. Juveniles are a pale green colour with long dark spots on the scales that may form bars. There are two black lines situated at the back of the eye and a yellow margin extends to the caudal fin. It has a total of 9 dorsal spines, 10 dorsal soft rays, 3 anal spines and 8 anal soft rays.
Individuals of this species are hermaphrodites, having the ability to change from female to male. This usually happens after 9 years but it is not known what trigger the developmental change. The sex ratio for this species is female biased. Maximum recorded age is 32 years.
This species is present across the Indo-Pacific: from the Red Sea to South Africa and to the Tuamoto Islands, North to the Ryukyu Islands, South to New Caledonia. Moreover, it is also present on offshore reefs of north-western Australia and the Great Barrier Reef. Recorded depth range is between 1 to 100 m, but it is more commonly found between 2 to 60 m depth.
It dwells in outer reef slopes, channel slopes and lagoon reefs. This fish species is mostly solitary but can be found in pairs. Juveniles are found in seagrass beds or coral rich areas of lagoon reefs where staghorn Acropora corals are abundant. Their presence is also noted in algae reefs.
Its diet consists of molluscs, fishes, sea urchins, crustaceans and other invertebrates. The Napoleon wrasse is also a predator to some toxic animals such as sea hares, boxfishes and the crown of thorns starfish.
Adults become sexually mature at 4 to 6 years. Spawning aggregations occur with over 100 individuals grouping together. Their eggs are planktonic and the larvae hatch and settle near coral reefs.
According to the IUCN Red list, this species is categorized as being ‘Endangered’. Population trend is declining; over 50% in over 30 years. It is widespread but is not a common species. There are seldom over 20 fish per hectare in habitats. It is one of the most valued fish commercially and it is part of live fish trade in China, moreover, it is fished illegally in certain areas. There are multiple management schemes in place for this species. It is also listed in Appendix Ii of CITES (Convention on International Trade in Endangered Species).
 Russell, ‘Cheilinus Undulatus’.
The Napoleon wrasse is the largest species of the Labridae family. It can reach a maximum length of 229 cm and has been recorded to weigh up to 180 kg.