Yellow Tang

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.

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), 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. A single specimen was filmed in the Mediterranean Sea in Spanish waters in 2008, a likely aquarium release. 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).

In the wild, yellow tangs feed on benthic, uncalcified and filamentous turf algae and other marine plant material, as well as some types of zooplankton. 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.

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. Natural predators include larger fish, sharks, crabs, and octopuses.

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.

The larvae of the yellow tang can drift more than 100 miles and reseed in a distant location.

The yellow tang is listed as least concern on the IUCN Red List. The tropical yellow tang is heavily fished by the aquarium trade. Every year, 300,000 to 500,000 yellow tang were collected from the wild in Hawaii alone. 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. By the late 1990s, their stocks were collapsing. Nine marine protected areas were established off the coast of Hawaii to protect them. Over 70% of the yellow tang's natural range is protected from collection and fishing.