Paracanthurus

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 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. The lower body is yellow in west-central Indian Ocean individuals, and bluish in Pacific individuals (4). Additionally, the blue color on the trunk of Paracanthurus loses pigmentation in response to changes in light 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. Vagrants were found on two 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, Republic 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. ==Ecology==

Paracanthurus is a diurnal It is found in clear water on exposed outer reef areas or in channels with a moderate or strong current. Diet As a juvenile, its diet consists primarily of plankton. Adults are omnivorous and feed on zooplankton, but will also graze on filamentous algae. Life cycle Spawning takes place year round, with a peak between April and September. After hatching, these larvae rely on yolk reserves 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 popular culture==

In the 2003 Disney/Pixar animated film, Finding Nemo, one of the main characters, Dory (voiced by Ellen DeGeneres) is a regal blue tang suffering from short term memory loss. She and her parents, Jenny and Charlie (voiced by Diane Keaton and Eugene Levy), appear in the 2016 Disney/Pixar animated film sequel, Finding Dory. After the release of Finding Nemo in 2003, popular media outlets reported a rise in demand for clownfish, the co-star alongside blue tang in the film, to such an extent the phenomena was coined the Nemo effect. However, the legitimacy of the Nemo effect was disputed by peer-reviewed analysis. Nonetheless, a similar wave of rumors circulated the Internet following the release of Finding Dory in 2016. According to peer-reviewed analysis, online searches for blue tang increased for two to three weeks after the release of Finding Dory, though data on imports of Paracanthurus show there was no significant increase in imports of blue tang following the release of the film. ==Conservation==

The species is classified as Least concern by the IUCN. No population declines were found when last assessed by IUCN in 2010. Its current population trend is unknown and there is insufficient data on catch. While rare throughout its range, it is widespread geographically. Its distribution overlaps with multiple marine protected areas. ==References==