cockoo wrasse

Cuckoo wrasse

Latin name: Labrus mixtus
Global Distribution: East Atlantic, ranging from Norway south to Senegal, Azores, Madeira and the Mediterranean
UK Distribution: Most of the coast of Britain and Ireland
Size: up to 35cm in length
Diet: Barnacles, other crustaceans, and molluscs
Habitat: Over rocks and hard ground, and in the algal zone, between 2 – 200 m but mainly between 20 – 80 m

Until recently, the Cuckoo wrasse was not a popular species among fishermen as it did not have any commercial value but its vibrant colours made it very popular with public and private aquaria. However for the past decade, all wrasse have been targeted commercially for their use as cleaner fish in salmon cages.

The colours between the sexes vary with the females being orange-red with 2-3 dark and white spots on the rear dorsal and adjacent tail fin, and the males having a dark blue head with bright blue lines down their orange bodies. All wrasse have thick protruding lips, and there are strong teeth, both in the jaws (for biting and rasping) and on the pharyngeal bones in the throat (for gripping and crushing). With these teeth they are able to enjoy a mixed menu of shelled animals including barnacles, other crustaceans, and molluscs. The species have a special ritual for preparing the nest, during which they collect small stones or find a rocky area and, after cleaning it with their teeth, they bind the rocks with seaweed and mucus. When the nest is ready, the male invites the female to lay her eggs, which he then fertilises and guards until they hatch. They are slow growing and can live for up to 20 years.

Fun facts

  • The name cuckoo wrasse was coined by Cornish fishermen who compared the blue coloured males with bluebell flowers, which in cornish translates as the “Cuckoo flower”.
  • Females can change to males if there are no males in the immediate vicinity.
  • Around the Isle of Arran these wrasse could be used as an ‘environmentally friendly’ means of controlling sea lice outbreaks in salmon farms, but there is a risk that they could be fished unsustainably for this purpose.