Tangs belong to the family Acanthuridae. A purely saltwater fish at least 50 million years old, the name is interchangeable at times with surgeonfish and doctorfish species. Fish labeled as tangs appear to more often have a sharper, pointier nose than a fish labeled as a surgeonfish. All tang species are laterally compressed with a single, continuous dorsal fin. At the base of the tail, there are one or few sharp spines that can be used to slash a predator in self-defense. Tangs are a popular tropical fish for divers, snorkelers and collectors because of their patterns and coloration. Tangs may be solid, striped or spotted to name a few pattern variations. There also seems to be numerous colors that accompany the species including blue, yellow, red and black.
They are diurnal omnivores that will scrape organisms off of rocks and corals with their small mouths, but many species consume only algae. If a tang tends to consume more sand and coral when foraging, the species will have a more specialized gizzard. They serve an important role in the ecosystem by maintaining algae levels. Too much algae cover can smother coral life. Fecal deposits from these fish also help promote coral growth. Tangs themselves may suffer from spot disease, otherwise known as “ich” caused by parasitic protozoans such as Cryptocaryon and Amyloodinium. However, this only seems to occur when kept in captivity, not the wild.
The larvae start in the pelagic zone before falling to the bottom and developing into juveniles. Maturity is reached after one or two years, and the biggest species can reach 200 cm in length. Depending on the species, adult tangs may be found along the bottom near shallow rocky shores and exposed coral reefs, or above sandy areas where they can feed on plankton. There is sexual dimorphism by size among species, but it’s not usually a permanent dimorphism. Tangs are active swimmers with a bold presence and active demeanor. They need a larger tank for these reasons. While they can be territorial, tangs are relatively good in large communities of fish. While there are no huge conservation threats at the moment for these fish, it should be noted that studies have shown blue tangs testing positive 57% of the time for cyanide presence. Collectors appear to heavily traffic blue and hippo tangs from the wild. Some good news is the blue tang has recently been bred in captivity for the first time. There aren’t enough captive blue tangs though to provide to consumers at the moment.