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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. It is also notable for having potentially passed the mirror test, though this is not without controversy. Taxonomy 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.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. Description  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. Distribution The bluestreak cleaner wrasse is found on coral reefs in the tropics from the Red Sea and Indian Ocean to the western Pacific (including Papua New Guinea, Japan, Fiji, and French Polynesia).[5] It was first recorded from the Kermadec Islands Marine Reserve north of New Zealand in 2015, after researchers examined hundreds of hours of unused documentary film footage. Cleaning 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.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, 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.) The bluestreak cleaner wrasse is known to clean balaenopteridae, chondrichthyans, homaridae, octopodidae, and dermochelyidae In different regions, the bluestreak cleaner wrasse displays various degrees of dependency on clients' ectoparasites as a primary food source. In tidal environments such as the Great Barrier Reef, the bluestreak cleaner wrasse is a facultative cleaner that feeds more on corals than on fish clientele.Juvenile bluestreak cleaners are seen to bite their clients more often than the adults within that region, thus changing the dynamic of the known mutualistic relationship.However, in regions where the bluestreak cleaners are solely dependent on clients' parasites, fish who have access to cleaning services have better body condition than those without cleaner access. In the Marsa Bareika of the Ras Mohamed Nature Reserve, Egypt, the bluestreak cleaner wrasse live in specific sectors of the shallow reefs and are shown to rely on ectoparasites from species such as the brown surgeonfish and white belly damselfish. In this region, fish that visit cleaner wrasses have lower antibody responses than those without cleaner access, suggesting that cleaner access may decrease the need for active immunity. Reproduction Cleaner wrasse males defend specific living territories from other males in which they are able to have control over the females in those territories. When the dominant male no longer exists in that territory, one of the larger females is able to change sexes to take control over that territory.

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Acanthurus leucosternon, commonly known as the blue surgeonfish, powder blue tang or powder-blue surgeonfish, is a species of marine ray-finned fish belonging to the family Acanthuridae, the surgeonfishes, unicornfishes and tangs. This species is found in the Indian Ocean. Taxonomy Acanthurus leucosternon was first formally described in 1833 by the English naturalist Edward Turner Bennett with its type locality given as Sri Lanka. The genus Acanthurus is one of two genera in the tribe Acanthurini which is one of three tribes in the subfamily Acanthurinae which is one of two subfamilies in the family Acanthuridae. Etymology Acanthurus leucosternon has the specific name leucosternon. This combines the Greek words leukos, meaning "white", and sternon, meaning "breast"; this refers to the white chest shown by this species. Description The fish can reach an average size of 23 cm (9 in) in length. The body has an oval shape and is compressed laterally. Like other surgeonfishes, Acanthurus leucosternon swims with its pectoral fins. The caudal fin has a crescent shape. The fish has a "surgeon's scalpel," an erected part of the spine located at the base of the tail. The mouth is small and pointed in a beak-like manner with tiny and sharp teeth for reaching narrow spaces of food. Its sides are blue; its dorsal fin and the base of caudal fin are yellow; the head is black; the mouth, the throat area, the anal and pelvic fins are white. The pectoral fins are transparent with yellow reflections. The intensity of its blue color shows off if the fish is healthy or not.[citation needed] The fish does not undergo color changes as it matures; as some tangs, surgeonfish and unicornfish do. Distribution and habitat Acanthurus leucosternon is found in tropical waters from the Indian Ocean. The species inhabits shallow and clear coastal waters always associated with a reef. It prefers flat top reefs and areas along seaward slopes. Behaviour The powder blue tang, like most fish in the family Acanthuridae, is herbivorous, eating mostly benthic algae.Acanthurus leucosternon has a diurnal activity. It is solitary, territorial and aggressive with other surgeonfish. In cases where food is plentiful, it may feed in shoals, but in cases of scarcity, it may compete individually for food. It may use its surgeon's scalpel as a defensive weapon.

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Halichoeres chrysus, commonly called the canary wrasse, golden wrasse or yellow wrasse, is a fish species in the wrasse family native to central Indo-Pacific area. Description The canary wrasse is a small fish that can reach a maximum length of 12 cm. It has a thin, elongate body with a terminal mouth. Body coloration is bright yellow with a few variations according to age. Juvenile and immature female have two black spots rimmed with white or light yellow on the dorsal fin (the first one at the start of the fin (head side) and the second in the middle of its dorsal fin) and a third one between the caudal peduncle and the start of the caudal fin. Mature females or young males only show the two black spots on the dorsal fin. Mature males display only the first black spot on the front of the dorsal fin, a lighter-colored spot just behind the eye and irregular greenish to pinkish lines on the face. Distribution and habitat The canary wrasse is widespread throughout the tropical and subtropical waters of the central Indo-Pacific, in an area bordered by the Christmas Islands and Indonesia, Japan, New South Wales and the Rowley Shoals, and the Tonga Islands  and Solomon Islands. This wrasse occurs on outside reef slopes, in rubble and sandy areas from surface down to a depth of 30 meters. Biology The canary wrasse lives in small groups. It is a benthic predator that feeds mainly on small marine invertebrates such as crustaceans, molluscs, worms and echinoderms captured on or in the substrate. Like most wrasse, the canary wrasse is a protogynous hermaphrodite, i.e. individuals start life as females with the capability of turning male later on.

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Naso vlamingii, the bignose unicornfish, scibbled unicornfish, Vlaming's unicornfish, and zebra unicornfish, is a species of marine ray-finned fish belonging to the family Acanthuridae, the surgeonfishes, unicornfishes and tangs. This species is found in the Indo-Pacific. Taxonomy Naso vlamingii was first formally described as Naseus vlamingii in 1835 by the French zoologist Achille Valenciennes with its type locality given as Molucca Island in Indonesia.[3] This species is classified within the nominate subgenus of the genus Naso.[4] The genus Naso is the only genus in the subfamily Nasinae in the family Acanthuridae. Etymology Naso vlamingii has the specific name which honours the Dutch explorer Admiral Cornelis de Vlamingh who collected specimens and drew illustrations of fishes for the Muséum national d’Histoire naturelle and Valenciennes based his description on one of Vlamingh's illustrations.[4] Description Naso vlamingii has 6 spines and 26 or 27 soft rays all of similar height supporting the tall dorsal fin and 2 spines and between 27 and 29 soft rays supporting the anal fin. It has a relatively deep body with standard lengths ranging from 2.2, in subadults, to 2.6, in adults, times the body's depth. There is an obvious bulbous protuberance growing from the head above the snout. There are two bony plates on each side of the caudal peduncle and these have keels with anterior pointing spines. The adults develop long filaments from the tips of the caudal fin lobes. The overall colour of the adults is greyish-brown or reddish brown, and they have the ability to change colour quickly, with small dark blue spots on the head and upper flanks. These spots join up to form stripes on the lower flanks. There is a wide blue band running from the eye to the front of the bulbous protuberance. The lips are blue and there is an irregular blue blotch to the rear of the base of the pectoral fin. The caudal fin is blue at its base, grey in the middle with an ill-defined yellow marginand blue outer edges of the lobes and this extends onto the filaments. The intensity of the colour of the blue markings can be increased to a brilliant blue when the fish is displaying in courtship or to communicate with cleaner fish at cleaning stations.This species has a maximum published length of 60 cm (24 in). Distribution and habitat Naso vlamingii has a wide Indo-Pacific range which extends from the eastern coast of Africa between Kenya and South Africa, through the Indian Ocean islands, but it is absent the continental southern Asian waters, through the Andaman Sea, Indonesia and into the Pacific. In the Pacific it extends north to southern Japan, east to the Galápagos Islands and south to New Caledonia and Australia.[1] In Australia the species is found at a number of offshore islands and reefs, as well as from the northern Great Barrier Reef south to waters off Sydney in New South Wales and in the waters around Lord Howe Island in the Tasman Sea. The bignose unicornfish is found in deep lagoons and seaward reefs, frequently aggregating in schools that feed on zooplankton around the higher areas of deep slopes and drop-offs. Biology Naso vlamingii can live up to 40 years in captivity.[8] Their eggs are fertilized externally after being released in batches by the female. Spawning typically occurs in aggregations, where many individuals come together to release their eggs and sperm simultaneously. They change their feeding pattern throughout their lives. Juveniles are herbivores; feeding mainly with algae, semi-adults are omnivores and adults are primarily carnivores; hunting for zooplankton. 

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Zebrasoma xanthurum, the purple tang or yellowtail tang, is a species of marine ray-finned fish belonging to the family Acanthuridae which includes the surgeonfishes, unicornfishes and tangs. This species is endemic to the north western Indian Ocean. Taxonomy Zebrasoma xanthurum was first formally described as Acanthurus xanthurus in 1852 by the English zoologist Edward Blyth with its type locality given as Sri Lanka. However, this species has not reliably been recorded in Sri Lanka since Blyth's description and the type locality may be erroneous. The yellowtail tang is part of a species pair within the genus Zebrasoma, along with the longnose tang (Z. rostratum). The genera Zebrasoma and Paracanthurus make up the tribe Zebrasomini within the subfamily Acanthurinae in the family Acanthuridae, according to the 5th edition of Fishes of the World. Etymology Zebrasoma xanthurum has the specific name xanthurum, meaning “yellow tail”, a reference to the yellow caudal fin of this species. Description Zebrasoma xanthurum has its dorsal fin supported by 5 spines and 24 or 25 soft rays while the anal fin is supported by 3 spines and 19 or 20 soft rays.This species has a deep laterally compressed body, a protruding snout and high dorsal and anal fins.The depth of the body fits 1.7 to 1.9 times into its standard length while the longest dorsal fin ray fits 3.3 to 3.7 times into the standard length. The snout has a concave profile on both the upper and lower sides. There is a velvet-like patch of bristles on the caudal peduncle anterior to the spine. The juveniles have a rounded caudal fin but in adults it may be slightly rounded or truncate. The head and body of adults are dark blue to purple, contrasting with the bright yellow caudal fin. The head and anterior part of the body are marked with black spots and these extend onto the adjacent fins. There are irregular black horizontal lines on the rest of the body and fins apart from the caudal fin and the pectoral fins have the outer third coloured yellow. Juveniles and subadults have dark brown longitudinal lines on their bodies. The yellowtail tang has a maximum published total length of 36.7 cm (14.4 in), although a total length of 10 cm (3.9 in) is more typical. Distribution and habitat Zebrasoma xanthurum is endemic to the north western Indian Ocean where it is found in the Red Sea and the Gulf of Aden and around the coasts of the Arabian Peninsula into the Persian Gulf. It is also found around Socotra. A record from Sardinia in 2015 is thought to be an aquarium release. A record from the Maldives is thought to be a misidentification and the type locality of Sri Lanka is thought to be an error. These fishes are found in groups at depths down to 20 m (66 ft) over coral rich or rocky areas. Biology Zebrasoma xanthurum is a herbivorous grazer of filamentous algae. They follow a daily pattern of feeding in single individuals or pairs during the day and at sunset the stop feeding and move into their shelter for the night among corals or in crevices. The juveniles are cryptic and hide among coral. Conservation status Zebrasoma xanthurum is a minor item in the aquarium trade. The IUCN assess its conservation status on a global level as Least Concern, but in the Persian Gulf it has a small area of suitable habitat that is subject to destruction by coastal development and is assessed as Vulnerable.

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Naso lituratus, the clown unicornfish, orangespined unicornfish, black-finned unicornfish, Pacific orangespined unicornfish, blackfinned unicornfish or stripefaced unicornfish, is a species of marine ray-finned fish belonging to the family Acanthuridae, the surgeonfishes, unicornfishes and tangs. This fish is found in the eastern Indian Ocean and western Pacific Ocean. Unique to members of Acanthuridae, including Naso lituratus, are the Epulopiscium bacteria. These bacteria influence the digestion of Naso lituratus, helping them process the algae in their diet.[3][4][5] Naso lituratus can be found in the Indian Ocean and the Pacific Ocean. This species can be easily recognised by two bright orange forward-hooked spines on the caudal peduncle (the tail base), its orange lips and black face mask. The body is brownish grey with yellow nape and there is a broad black band on the dorsal fin. It reaches about 45 cm (18 in) in length. It can be found on coral reefs, often in pairs. Taxonomy Naso lituratus was first formally described in 1801 as Acanthurus lituratus by the German naturalist Johann Reinhold Forster without stating a type locality, although this is considered to be Tahiti in the Society Islands of French Polynesia.[7] This species is classified within the nominate subgenus of the genus Naso.[8] The genus Naso is the only genus in the subfamily Nasinae in the family Acanthuridae. Description and biology The features of Naso lituratus include orange lips, a caudal peduncle with a brash-hooked spine, and a black face mask. The descriptions of these features include one dorsal fin on top of head and is encircled by a broad black band around 45 centimeters long. They barely grow in size. Long anal fin with II spines and 28–30 soft rays, and a continuous, unnotched dorsal fin with VI spines and 27–30 soft rays. Contains 8 to 9 gill rakers on the lower leg whereas the upper limb has 4. There are 6 spines in total, each with 26–29 soft rays. Adipose fins do not exist. There is one anal fin, two spines overall, and between 27 and 30 soft rays on it. The pectoral and pelvic fins are two of its paired fins. The pectoral fin contains 17–18 soft rays and 0 spines. The pelvic fin has a single spine and three soft rays. In adult males, the lobe's apex produces a lengthy filament. Caudal fin is lunate or crescent-shaped. Two sharp blades that point forward are on the caudal peduncle. In Juveniles, their blades are not fully grown, as they have a stifling gray-brown tint with black, yellow, and white patterns. No forehead "horns" or front protuberance that can be seen in certain other Acanthuridae species. Distribution and habitat Naso lituratus live in the East Indian and Pacific Ocean, with their habitat is living in the coral reefs that lay around in those specified oceans. The reproduction of this species are that the sexes are separate among the Acanthuridae and have distinct differences in size. Spawning occurs year round in Guam. They need high oxygen levels, strong water currents, same companions and need to feed on wild algae. Their self defense tactic is that they will extend their strong tail spines to strike any approaching predators. Naso lituratus has various human use including as a food source and as a commodity in the pet and aquarium trade.

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The yellow tang (Zebrasoma flavescens), also known as the lemon sailfin, yellow sailfin tang or somber surgeonfish, is a species of marine ray-finned fish belonging to the family Acanthuridae which includes the surgeonfishes, unicornfishes and tangs. Bright yellow in color, it is one of the most popular marine aquarium fish, though in its natural state, it lives in reefs. The yellow tang spawns around a full moon, eats algae, and has a white barb, located just before the tail fin, to protect itself. Taxonomy and etymology The yellow tang was first formally described by English naturalist Edward Turner Bennett as Acanthurus flavescens in 1828 from a collection in the Hawaiian Islands. Zebrasoma refers to the body and the zebra-like stripes or bars on the body of the type species the genus, the sailfin tang (Z. velifer). Its species name is the Latin adjective flavescens, which refers to the tang's yellow color. Within the genus Zebrasoma the yellow tang forms a species pair with the scopas tang (Z. scopas).[5] The genera Zebrasoma is one of two genera that make up the tribe Zebrasomini within the subfamily Acanthurinae of the family Acanthuridae. Evolution and genetics Based on the gene Cytochrome C-oxidase 1 (CO1), a group of researchers was able to reconstruct the phylogenetic tree of the genus Zebrasoma with mitochondrial barcoding sequences. Description and biology   Adult fish can grow to 20 centimetres (7.9 in) in length, and 1–2 centimetres (0.39–0.79 in) in thickness. Adult males tend to be larger than females. Yellow tangs are bright yellow in color. At night, the yellow coloring fades slightly, and a prominent brownish patch develops in the middle with a horizontal white band. They rapidly regain their bright yellow color during daylight. They can be aggressive, are prone to marine ich, and may damage coral within a reef tank. Male and female yellow tang look very similar. When mating, however, males change color and have a "shimmering" behavior which makes them identifiable.The yellow tang has 5 dorsal spines along with 23–26 dorsal soft rays. The yellow tang also has 3 anal spines as well as 19–22 anal soft rays. There is a white spine on its caudal peduncle that it can use for defense. Its snout is moderately protruding. Its mouth is small with spatulate teeth that are place classed relatively close together inside of the yellow tang's mouth. In juveniles, there are 12 upper and 14 lower teeth. In adults, there are 18 upper and 22 lower teeth. The yellow tang is a marine fish that lives in reefs and is typically found by itself or in small groups/schools. It is mainly herbivorous and eats filamentous algae. Reproduction Spawning happens throughout the year, and it peaks once, normally occurring around the time the moon is full, so this suggests there is some sort of lunar periodicity to the spawning behavior. Spawning happens in pairs or groups, and fertilization is external. Eggs are left in open water and yellow tang are substratum egg scatterers. Yellow tang do not guard their eggs, and once the eggs hatch, the juveniles receive no parental care. Food In the wild, yellow tangs feed on benthic turf algae and other marine plant material. In captivity, they are commonly fed meat/fish-based aquarium food, but the long-term health effects of this diet are questionable. However, most experts in the marine aquarium industry express little scepticism that such a well rounded and balanced diet including plant and animal material would be in any way detrimental to mostly herbivorous fishes like tangs since they still need on occasion, complex amino acids and nutrients that only ocean animals can provide. In the wild, yellow tangs provide cleaner services to marine turtles, by removing algal growth from their shells. Distribution and habitat It is commonly found in shallow reefs, from 2–46 metres (6.6–150.9 ft) deep, in the Pacific Ocean (Ryukyu, Mariana, Marshall, Marcus, Wake, and Hawaiian islands),[3] west of Hawaii and east of Japan. There have also been reports that they have been found off the coast of Florida in the Western Central Atlantic.[9] A single specimen was filmed in the Mediterranean Sea in spanish waters in 2008, a likely aquarium release.[10] As of July of 2024, yellow tangs have been spotted several times on the shallow reefs of Mexico’s Riviera Maya. Their habitat is tropical with a temperature range of 24–28 °C (75–82 °F). Hawaii was the most common place for aquarium harvesting, prior to the export ban, where up to 70% of the yellow tangs for the aquarium industry were sourced from. Over 70% of the yellow tang's natural range is protected from collection and fishing. The yellow tang is listed as "Least Concern" by the International Union for Conservation of Nature (IUCN). Predators and other threats The yellow tang has many natural predators, including larger fish, sharks, crabs, and octopuses. Another threat is habitat destruction that is caused by humans. Examples of habitat destruction caused by humans are pollution that started on land and flows into the water, physical damage and destruction from harmful fishing practices, as well as overfishing, coral harvesting, and snorkeling, which can potentially cause reef damage. Conservation status Conservation status is labelled as least concern, but there are many ways yellow tang are being protected. The most prominent is that yellow tangs are being bred in captivity for aquarium use now more than they were, so collecting yellow tang from the ocean has decreased sharply. This allows wild yellow tang to be able to thrive without too many being taken, so the species is more likely to survive. In 2010, one study found that fish larvae can drift on ocean currents and reseed fish stocks at a distant location. This finding demonstrated that fish populations can be connected to distant locations through the process of larval drift. They investigated the yellow tang, because larva of this species stay in the general area of the reef in which they first settle. The tropical yellow tang is heavily fished by the aquarium trade. By the late 1990s, their stocks were collapsing. Nine MPAs were established off the coast of Hawaii to protect them. Larval drift has helped them establish themselves in different locations, and the fishery is recovering. "We've clearly shown that fish larvae that were spawned inside marine reserves can drift with currents and replenish fished areas long distances away," said coauthor Mark Hixon. In the aquarium The yellow tang is very commonly kept as a saltwater aquarium fish. In 2015, researchers successfully bred them in captivity. Captive-bred yellow tangs are now routinely available for purchase at fish stores and online vendors. They can grow up to 8 inches (20 cm) in the wild, but are introduced to aquariums in the 2-to-4-inch (5.1 to 10.2 cm) range. Some specimens as large as 6 inches (15 cm) are occasionally available. Life expectancy in the wild can exceed 30 years.  

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Zebrasoma desjardinii, the Red Sea sailfin tang, Desjardin's sailfin tang, Indian sailfin tang or Indian sailfin surgeonfish, is a species of marine ray-finned fish belonging to the family Acanthuridae, the surgeonfishes, unicornfishes and tangs. This fish is found in the Indian Ocean. Taxonomy Zebrasoma desjardinii was first formally described in 1836 as Acanthurus desjardinii by the English zoologist Edward Turner Bennett with its type locality given as Mauritius. In the past, this taxon was treated as conspecific or synonymous with Zebrasoma velifer.The genera Zebrasoma and Paracanthurus make up the tribe Zebrasomini within the subfamily Acanthurinae in the family Acanthuridae, according to the 5th edition of Fishes of the World. Etymology The specific name of Zebrasoma desjardinii honours the French zoologist Julien Desjardins; he lived for a number of years in Mauritius and donated a collection of fishes to the British Museum of Natural History, including the type of this species. Description Zebrasoma desjardinii has a tall dorsal fin that has 4 spines and between 27 and 31 soft rays (the longest of which is around half of the standard length), while these figures for the anal fin are 2 and between 22 and 24 respectively. It has a deep body, with the standard length being 1.8 to 2 times its depth; the maximum published total length of this species is 40 cm (16 in). The mouth protrudes with a concave profile on the snout. The spine in the caudal peduncle has a narrow posterior connection to the body, and the caudal fin is truncate. The body is grey, with around 8 dark grey vertical bars; each bar houses 2 to 3 orange or yellow vertical lines, which break up into spots towards the lower body and on the anal fin. There are 2 dark brown bars on the head, with the first one passing through the eye. There is a dense pattern of small, light yellow spots on the head and body, and a similar pattern of spots arranged in bands can be on the dorsal fin. The caudal fin is marked with pale blue spots. The juveniles have slender grey and yellow bars on the body and 2 black bars on the head. Distribution and habitat Zebrasoma desjardinii is found in the Indian Ocean. It can be found off the eastern coast of Africa (as south as Sodwana Bay, South Africa), as well as in the Middle East, including off the coasts of Israel, Saudi Arabia and Yemen. It is also found across the islands of the Indian Ocean (such as Sri Lanka, islands in the Andaman Sea, Sumatra, Java, the Cocos (Keeling) Islands and Christmas Island). In 1999, a pair of this species was recorded in the Atlantic Ocean, off Florida, but this was probably due to aquarium release. Zebrasoma desjardinii is found at depths between 1 and 30 m (3 ft 3 in and 98 ft 5 in) in lagoon and seaward reefs, although the juveniles are more typically found in sheltered areas within reefs. Behaviour Zebrasoma desjardinii adults usually can be found in pairs, while juveniles are solitary.They feed primarily on filamentous algae, macroalgae and plankton, but individuals in the Red Sea have been regularly observed feeding on moon jellies (Scyphozoa) and comb jellies (Ctenophora) as well.[10] This species may form aggregations while feeding on algae; if they do so within the territory of the predatory slingjaw wrasse, the wrasse may darken its colour so as to match the colour of the tangs. The wrasse then joins in the aggregation and mimics their algae-feeding actions while hunting prey. Zebrasoma desjardinii is a pair spawner; while this is a typical trait of other fish in its genus, group spawning is more common at the family level.

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Paracanthurus hepatus is a species of Indo-Pacific surgeonfish. A popular fish in marine aquaria, it is the only member of the genus Paracanthurus. A number of common names are attributed to the species, including regal tang, palette surgeonfish, blue tang , royal blue tang, hippo tang, blue hippo tang, flagtail surgeonfish, Pacific regal blue tang, and blue surgeonfish, hepatus tang, Indo-Pacific blue tang, regal blue surgeonfish, wedge-tailed tang, wedgetail blue tang. Description Paracanthurus hepatus has a royal blue body, yellow tail, and black "palette" design. Its length at first sexual maturity is 149.2 mm. Adults typically weigh around 600 g (21 oz) and males are generally larger than females.The back has a broad black area that encloses at the tip of the pectoral, creating a blue oval on each side of the fish that extends in the direction of the eye. The tail has a bright yellow triangle with its apex anterior to the caudal spine and its base at the posterior end of the caudal fin. Black surrounds the triangle on the upper and lower lobes of the caudal fin, in the same hue as the back area. Paracanthurus has small small scales, each with short ctenii on the upper surface. Scales on the caudal spine possess ctenii approximately three times as long as scales on the rest of the body. Scales anteriorly placed on the head between the eye and the upper jaw are larger with tuberculated, bony plates. This fish has a compressed, elliptical body shape, and a terminal snout. It has nine dorsal spines, 26–28 dorsal soft rays, three anal spines, and 24–26 anal soft yellow rays, and 16 principal caudal rays with slightly projecting upper and lower lobes. Its pelvic fin is made up of one spine and three rays; this characteristic is considered a synapomorphy of the Naso and Paracanthurus genus. The caudal peduncle has a spine located in a shallow groove, which is also a characteristic of its sister taxa Zebrasoma. It has 22 vertebrae. Paracanthurus has teeth that are small, close-set, denticulated, and described as incisor-like. Jaw morphology includes an ectopterygoid that links the palatine to the quadrate near the articular condyle. A crest is present on the anterodorsal surface of the hyomandibular. The opercle is less developed, with a distinctly convex profile. Some slight variation in appearance is present within Paracanthurus. The lower body is yellow in west-central Indian Ocean individuals, and bluish in Pacific individuals . Additionally, the blue color on the trunk of Paracanthurus loses pigmentation in response to changes in light and/or melatonin levels, making its appearance slightly lighter in color at night. Distribution The regal blue tang can be found throughout the Indo-Pacific. It is seen in the reefs of the Philippines, Indonesia, Japan, the Great Barrier Reef of Australia, New Caledonia, Samoa, East Africa, and Sri Lanka. A single specimen was photographed in 2015 in the Mediterranean Sea off Israel. Vagrants were found two separate occasions in Hawaii, and are assumed to be aquarium releases. Paracanthurus is an extant resident in the following territories: American Samoa; Australia; British Indian Ocean Territory; Brunei Darussalam; Christmas Island; Cocos (Keeling) Islands; Comoros; Cook Islands; Disputed Territory (Paracel Is., Spratly Is.); Fiji; French Southern Territories (Mozambique Channel Is.); Guam; India (Nicobar Is., Andaman Is.); Indonesia; Japan; Kenya; Kiribati (Kiribati Line Is., Phoenix Is., Gilbert Is.); Madagascar; Malaysia; Maldives; Marshall Islands; Mauritius; Mayotte; Micronesia, Federated States of ; Myanmar; Nauru; New Caledonia; Niue; Northern Mariana Islands; Palau; Papua New Guinea; Philippines; Réunion; Samoa; Seychelles; Singapore; Solomon Islands; Somalia; South Africa; Sri Lanka; Taiwan, Province of China; Tanzania, United Republic of; Thailand; Timor-Leste; Tokelau; Tonga; Tuvalu; United States (Hawaiian Is.); United States Minor Outlying Islands (US Line Is., Howland-Baker Is.); Vanuatu; Viet Nam; Wallis and Futuna. Ecolog Paracanthurus is a diurnal marine species that occupies marine neritic habitats along coastlines. It is found in clear water on exposed outer reef areas or in channels with a moderate or strong current. It primarily utilizes coral reef habitats, but is also known to utilize seagrass beds, mangroves, algal beds, and rocky reefs [1]. It has an upper and lower depth limit of 2 meters and 40 meters, respectively .They live in pairs or small groups of 8 to 14 individuals. They can also be found near cauliflower corals on the seaweed side of coral reefs. Juveniles can be found in schools using Acropora for shelter. Numbers of males and females tend to maintain a 1:1 ratio. The fish is important for coral health as it eats algae that may otherwise choke it by overgrowth. Diet As a juvenile, its diet consists primarily of plankton. Adults are omnivorous and feed on zooplankton, but will also graze on filamentous algae.[16] Life cycle Spawning takes place year round, with a peak between April and September. Spawning occurs during late afternoon and evening hours around outer reef slopes. This event is indicated by a change in color from a uniform dark blue to a pale blue. Males aggressively court female members of the school, leading to a quick upward spawning rush toward the surface of the water during which eggs and sperm are released. The eggs are small, approximately 0.8 millimetres (1⁄32 in) in diameter. The eggs are pelagic, each containing a single droplet of oil for flotation. The fertilized eggs hatch in twenty-four hours, revealing small, translucent larvae with silvery abdomens and rudimentary caudal spines. Once opaque, the black "palette" pattern on juveniles do not fully connect until mature. These fish reach sexual maturity at 9–12 months of age, and at approximately 149.22 mm in size.[6] Fecundity has a tendency to positively correlate with weight. Fishes in the family Acanthuridae, including Paracanthurus, produce altricial larvae that receive no v. parental care. After hatching, these larvae rely on yolk reserves in order to survive their first two to three days of life. Importance to humans The regal blue tang is of minor commercial fisheries importance; however, it is a bait fish. The flesh has a strong odor and is not highly prized. This fish may cause ciguatera poisoning if consumed by humans. However, regal blue tangs are collected commercially for the aquarium trade. Handling the tang risks the chances of being badly cut by the caudal spine. These spines, one on each of the two sides of the caudal peduncle, the area where the tail joins the rest of the body, are extended when the fish is stressed. The quick, thrashing sideways motion of the tail can produce deep wounds that result in swelling and discoloration, posing a risk of infection. It is believed that some species of Acanthurus have venom glands while others do not. The spines are used only as a method of protection against aggressors. The regal blue tang is one of the most common and most popular marine aquarium fish all over the world, holding its place as the 8th most traded species worldwide. In 1997–2002, 74,557 individuals were traded in official tracked sales and in 2011 approximately 95,000 Paracanthurus were imported for use as a marine ornamental fish. When harvesting Paracanthurus in the wild, juveniles are specifically targeted since they are easiest to collect due to their tendency to travel in schools. Paracanthurus for human use are harvested in the wild rather than raised in aquaculture. Conservationists encourage efforts to switch to aquaculture in order to better preserve wild populations.

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