Bluestreak Cleaner Wrasse

The bluestreak cleaner wrasse (Labroides dimidiatus) is one of several species of cleaner wrasses found on coral reefs from Eastern Africa and the Red Sea to French Polynesia. Like other cleaner wrasses, it eats parasites and dead tissue off larger fishes‘ skin in a mutualistic relationship that provides food and protection for the wrasse, and considerable health benefits for the other fishes.^[3][4][5] It is also notable for having potentially passed the mirror test, though this is not without controversy.^[6][7][8][9]

This is a small wrasse, averaging 10 cm (3.9 in) long, at most 14 cm (5.5 in). It can be recognized thanks to a wide longitudinal black stripe running along the side and eye; the back and the stomach are white (sometimes slightly yellowish). This white part changes to a bright blue on the front of the animal, while the black band widens at the tail. The young are black with an electric blue line.

A genetic analysis of L. dimidiatus revealed the population fell into two monophyletic clades, with Indian Ocean populations generally having different stripe widths to western Pacific fishes. The Japanese cleaner wrasses, though, fell within the same group as Indian Ocean fish, despite differing in appearance, and both clades overlap around Papua New Guinea.^[5] Two closely related cleaner wrasse species, Labroides pectoralis and Labroides bicolor, were grouped inside the L. dimidiatus clade, so the bluestreak cleaner wrasse may in fact be polyphyletic, incorporating several species.^[5]

Cleaner wrasses are usually found at cleaning stations. Cleaning stations are occupied by different units of cleaner wrasses, such as a group of youths, a pair of adults, or a group of females accompanied by a dominant male. When visitors come near the cleaning stations, the cleaner wrasses greet the visitors by performing a dance-like motion in which they move their rear up and down.^[12] The visitors are referred to as “clients”. Bluestreak cleaner wrasses clean to consume ectoparasites on client fish for food. The bigger fish recognise them as cleaner fish because they have a lateral stripe along the length of their bodies,^[13] and by their movement patterns. Cleaner wrasses greet visitors in an effort to secure the food source and cleaning opportunity with the client. Upon recognising the cleaner and successfully soliciting its attention, the client fish adopts a species-specific pose to allow the cleaner access to its body surface, gills and sometimes mouth.^{[citation needed]} Other fish that engage in such cleaning behavior include goby fish (Elacatinus spp.)^[14] The bluestreak cleaner wrasse is known to clean balaenopteridae, chondrichthyans, homaridae, octopodidae, and dermochelyidae.