The corkwing wrasse (Symphodus melops) is a coastal wrasse, a fish of European waters.

Description

Its body is deep and compressed sideways with a single, long dorsal fin. It is usually about 15 cm (5.9 in) long, but has reached 25 cm (9.8 in).

It is highly variable in colour, depending on the environment and age of the fish. The corkwing wrasse has a black spot in the middle of the tail stalk, and a comma-shaped spot behind the eye. Females and juveniles tend to be brown or greenish-brown, while the males are typically more brightly coloured. Both sexes have lines on the head and gill covers which are brown and pale blue in the female, bright green or blue in the male.

It feeds on a large variety of prey, but mainly bivalves and copepods.

Reproduction

The males exhibit dimorphism, where the territorial males build a ball-shaped nest of seaweed in rock crevices or sedimentary areas, amongst seaweed or seagrasses. The nest has an entrance hole which the male guards aggressively. The other morph mimics the females and tries to sneak-fertilize. The sneakers are much smaller than the territorial males, and you can not visually distinguish between the sneaker morph and the females. As there is a trade-off between reproductive investment and growth the sneakers have much larger gonads related to body size than the territorial males. The sperm quality is also shown to be better for the sneaker as it is longer-lived. 5 - 20% of the males in a population tend to be sneakers.

Importance

The fish has from 1988 been commercially used because of its ability to remove parasites from other fish. It is today heavily fished and one may say exploited for the use in aquaculture to remove salmon louse (Lepeophtheirus salmonis).