Genicanthus

Zebra angelfish

Zebra angelfish, Genicanthus caudovittatus

In contrast to many other angelfish, which live in pairs, swallowtail angels, in the genus Genicanthus live like fairy basslets, with a dominant male guarding a harem of females. As with fairy basslets, if the male dies, the dominant female will become male and take charge of the harem. This species is found only in the Red Sea and the Western Indian Ocean. Only the male has the zebra pattern but only the female has the black stripes at the top and bottom of the tail, commemorated by the Latin name “caudovitatu”, which means “striped tail”.

Watanabe’s angelfish

Watanabe’s angelfish, Genicanthus watanabei

The ten species of swallowtail angelfish stand out among the marine angelfish family. Instead of staying close to the reef, and feeding on coral polyps and other stationary organisms, swallowtails consume plankton in the water column. While the sexes of other angelfishes are colored alike, male and female swallowtails look very different from each other. Only described to science in 1970, this species occurs off Japan and Australia, and far out into the Central Pacific, but is absent from the Indo-Pacific. Only the male has stripes.

Japanese swallowtail angelfish

Japanese swallowtail angelfish, Genicanthus semifasciatus

The males and females of all swallowtail angels differ in color, but in this case, the difference is so extreme that the male was given the species’ scientific name in 1934, while the female was described as “Holacanthus fuscosus” in 1970. Only aquarium observations confirmed they were the same species. In Japan, this species is found only in Okinawa and “The Seven Islands of Izu” (of which there are actually around a dozen). It is also found off Taiwan and the Philippines.

Bellus lyretail angelfish

Bellus lyretail angelfish, Genicanthus bellus

In most of the swallowtail angelfish species, the male has a more complicated pattern than the female. This species, found from the Philippines to remote islands of the South Pacific, is an exception. The male has a pattern of gold strips bordering a broad pinkish band. The female has a striking pattern of black, white, and purplish-blue. The Latin word “bellus” means “beautiful”. The Greek word “genicanthus” means “cheek spine”.

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