Blue Diesel Wrasse

Adult blue streak wrasses usually grow to be 4 inches long (Grant,1978).

Wrasses possess a smooth, compressed, elongate body with a pointed snout. They have small mouths with prominent lips. They have jaws and teeth, particularly 2 canines that are curved anteriorly in each jaw.

Wrasses have a rounded caudal fin along with a dorsal fin consisting of 9 spines and 9-11 rays and an anal fin with 2-3 spines and 9-10 rays (Marshall, 1964). Wrasses have very small scales and the head is normally scaleless.

Blue streak wrasses are brilliant blue with a broad jet-black band that runs from the tip of the snout to the end of the tail, starting out narrow at the anterior end and gradually broadening towards the posterior end. This band usually takes up most of the tail, except the upper and lower rays which are a shade of blue (Marshall, 1966). Young wrasses are sometimes all black, except for a pale streak along the lower, upper and back caudal rays (Marshall, 1964).

The colors of young and adult wrasses differ (Smith, 1965). They are also known to change colors based on mood (Grant, 1978).

There is no geographic variation in morphology or coloration.

Other Physical Features: bilateral symmetry

A similar species, L. aspidontus, closely resembles L. dimidiatus. Members of this species swim in an oscillating motion, as the wrasse does, and when larger fish open their mouths to be cleaned, swims inside and rips off pieces of skin (Roughley, 1951).

Perception Channels: tactile ; chemical

US Federal List: no special status

CITES: no special status

IUCN Red List of Threatened Species: least concern

Wrasses are not known to have any negative affects on humans.

Cleaner wrasses benefit humans by increasing the survival of various economically important fish. They increase the survival of larger fish by eating and removing harmful parasites and diseased tissue from their scales and body.

Wrasses are carnivorous. Their diet consists primarily of parasitic copepods and other invertebrates that are taken from the mouth and gill openings of larger fish. They also feed occasionally on free-swimming crustaceans.

Blue streak wrasses are known as common cleaner fish that set up cleaning stations on various parts of coral reefs, usually 3-10ft. deep. They attract larger fish to their stations by making strange, oscillatory swimming movements, and the fish then stop to get cleaned. Wrasses enter the mouth and gill openings and remove any ectoparasites and diseased tissue. The larger fish not only refrain from devouring these small cleaner fish, but actually readily open their mouth and gill cavities so that they are able to clean.

This is clearly a mutualistic relationship between cleaner wrasses and various larger fish of the ocean (Grant, 1978).

Blue streak wrasses inhabit Indo-pacific coral reefs, including the Great Barrier Reef. They range from Queensland and the South Seas through the East Indies to the Red Sea, Zanzibar and Mauritius (Marshall, 1964)

Biogeographic Regions: pacific ocean (Native )

Striped cleaner wrasses tend to dwell in coral or rocky areas on coral reefs (Roughley, 1951). They are commonly found in waters adjacent to shallow coral outcrops along the Great Barrier Reef (Grant, 1978). They are also seen in tide-pools. (Smith, 1965)

They are not migratory.

Aquatic Biomes: reef

Average lifespan
Status: captivity: 4 years.

Wrasses practice external fertilization in which the female's eggs are released into the water. Mating usually occurs at twilight (Flying Fish Express)

Large males defend reef territories and attract multiple females to these territories, usually by performing a beautiful mating dance. Females live within these territories and spawn with the male. Fertilized eggs form planktonic larvae that move freely with the ocean currents. If the territorial male leaves or dies, the most dominant female will take his role and become male within the next 24 hours. She assumes the territory and mates with the rest of the females.

Bi-directional sex change has been confirmed for this species (Ref. 103751). Oviparous, distinct pairing during breeding (Ref. 205). Pelagic spawners. Sex reversal is completed in 14-18 days (Ref. 34185, 34258). A monandric species (Ref. 55367). Length at sex change = 8.8 cm TL (Ref. 55367). Monogamous mating is observed as both facultative and social (Ref. 52884).

Often with yellow back in deep water (Ref. 48636). Scales on lateral line: 50-52 (+2 past hypural) (Ref. 1602).

Dorsal spines (total): 9; Dorsal soft rays (total): 10 - 11; Analspines: 3; Analsoft rays: 10

Inhabits coral rich areas of inner lagoons and subtidal reef flats to seaward reefs (Ref. 1602). Feeds on crustacean ectoparasites and mucus of other fishes (Ref. 9823, 48636). Monogamous (Ref. 52884). Stays in stations where other fish come to be cleaned. Cleaning intensity is not related to client size or commonness (Ref. 28019). Cleaning stations are occupied by a pair of adults, a group of juveniles or a group of females accompanied by a dominant male where a female becomes a functional male if the dominant male disappears (Ref. 5503). An unfamiliar visitor is usually greeted by dance-like movements with the tail maneuvering the back part of the body up and down. Juveniles behave this way when divers approach closely (Ref. 48636). A small body size and the presence of a lateral stripes both contribute as long-distance signals of cleaning services for fish clients (Ref. 75868).

Inhabits coral rich areas of inner lagoons and subtidal reef flats to seaward reefs (Ref. 1602). Feeds on crustacean ectoparasites and mucus of other fishes (Ref. 9823, 48636). Monogamous (Ref. 52884). A protogynous hermaphrodite (Ref. 55367). Stays in stations where other fish come to be cleaned. Cleaning intensity is not related to client size or commonness (Ref. 28019). Cleaning stations are occupied by a pair of adults, a group of juveniles or a group of females accompanied by a dominant male where a female becomes a functional male if the dominant male disappears (Ref. 5503). Some adults solitary and territorial. An unfamiliar visitor is usually greeted by dance-like movements with the tail maneuvering the back part of the body up and down. Juveniles behave this way when divers approach closely (Ref. 48636). Minimum depth range of 1 meter in Ref. 27115.

fisheries: of no interest; aquarium: commercial

分布於印度-太平洋區，由紅海、東非到萊恩、馬貴斯及杜夕群島，北至日本琉球與台灣海域，南至羅得豪島及拉帕等。台灣各地海域皆有分布。

小型之隆頭魚，體色鮮豔，是適合水族觀賞的魚類，非食用經濟魚種。在台灣較常見的魚醫生即是本種。

體長型，側扁；頭圓錐狀，口小，下唇分成兩片；齒小且尖，前方具對犬齒；前鰓蓋緣平滑；鱗片小，頰與鰓蓋被鱗；側線完全。D. IX, 11-12；A. III, 10；L.l. 52-53；尾鰭截形或稍圓形。體白色，體背較暗色，自口經眼至尾鰭具一漸寬的黑色帶；背鰭第一與第三棘間具一黑斑；臀鰭白色，基部具黑縱帶；尾鰭上下葉白色；偶鰭無色。

主要棲息於珊瑚礁區，深度範圍在1-20公尺之間，極常見的魚類。它有替其他的魚清理其身上寄生物的習性，因此有「魚醫生」的稱號，它可以將方圓15-30公尺以內的大型魚類，像石斑魚、蓋刺魚的皮膚、鰓蓋內或口腔內的寄生物體清得一乾二淨。這些大魚會改變體色或是擺出特別的動作姿態，向「魚醫生」表示需要清潔，進而張大了嘴，或把鰓蓋打開來，讓它在身上跑來跑去地清除細小橈腳類或甲殼類而這些體型巨大的魚類並不會傷害裂唇魚，反而一點兒也不介意，還好像很感激「魚醫生」替它們所做的服務，裂唇魚同樣地也會以特定的體色或動作來尋問是否需要幫忙。

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.

Inhabits coral rich areas of inner lagoons and subtidal reef flats to seaward reefs at depths of over 40 m (Ref. 1602). Feeds on crustacean ectoparasites and mucus of other fishes (Ref. 9823). Stays in stations where other fish come to be cleaned. Cleaning stations are occupied by a pair of adults, a group of juveniles or a group of females accompanied by a dominant male where a female becomes a functional male if the dominant male disappears (Ref. 5503).