The halfbanded angelfish (''Genicanthus semicinctus'') is a species of marine

ray-finned fish Actinopterygii (; ), members of which are known as ray-finned fishes, is a class of bony fish. They comprise over 50% of living vertebrate species. The ray-finned fishes are so called because their fins are webs of skin supported by bony or hor ...

, a

marine angelfish Marine angelfish are perciform fish of the family Pomacanthidae. They are found on shallow reefs in the tropical Atlantic, Indian, and mostly western Pacific Oceans. The family contains seven genera and about 86 species. They should not be confu ...

belonging to the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Pomacanthidae Marine angelfish are perciform fish of the family Pomacanthidae. They are found on shallow reefs in the tropical Atlantic, Indian, and mostly western Pacific Oceans. The family contains seven genera and about 86 species. They should not be confu ...

. It is found in the southwestern Pacific Ocean.

Description

''Genicanthus semicinctus'' like the other angelfishes in the

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

Genicanthus ''Genicanthus'' is a genus of marine angelfishes in the family (biology), family Pomacanthidae. Known commonly as swallowtail or lyretail angelfish, these fishes are so-named for the distinctive shape of their tailfins. This genus of angels, in ...

'', shows

sexual dichromatism Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most ani ...

, the males and females show differences in colour and pattern. The males are marked with thin close-set wavy black, vertical bars which run from the back to two-thirds down the flanks with the lower third of the body being yellowish-orange. They have a yellow

dorsal fin A dorsal fin is a fin located on the back of most marine and freshwater vertebrates within various taxa of the animal kingdom. Many species of animals possessing dorsal fins are not particularly closely related to each other, though through conv ...

and yellow lobes with long filaments on the

caudal fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as se ...

which has black spots. The chest also has black spots. The females are plain dark grey on the back with a whitish abdomen and have dark lobes to the caudal fin. Their fins have thin blue margins and there is a black blotch above the eye, this has a vivid blue margin. The dorsal fin contains 15 spines and 15-16 soft rays while the

anal fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as se ...

has 3 spines and 17 soft rays. This species attains a maximum

total length Fish measurement is the measuring of individual fish and various parts of their anatomies. These data are used in many areas of ichthyology, including taxonomy and fisheries biology. Overall length * Standard length (SL) is the length of a fish ...

of .

Distribution

''Genicanthus semicinctus'' is found in the southwestern Pacific Ocean. Here it is found only around

Lord Howe Island Lord Howe Island (; formerly Lord Howe's Island) is an irregularly crescent-shaped volcanic remnant in the Tasman Sea between Australia and New Zealand, part of the Australian state of New South Wales. It lies directly east of mainland P ...

, an Australian territory in the

Tasman Sea The Tasman Sea (Māori: ''Te Tai-o-Rēhua'', ) is a marginal sea of the South Pacific Ocean, situated between Australia and New Zealand. It measures about across and about from north to south. The sea was named after the Dutch explorer Abe ...

, and the

New Zealand outlying islands The New Zealand outlying islands are nine offshore island groups that are part of New Zealand, with all but Solander Islands lying beyond the 12nm limit of the mainland's territorial waters. Although considered an integral parts of New Zealand, ...

of the

Kermadec Islands The Kermadec Islands ( mi, Rangitāhua) are a subtropical island arc in the South Pacific Ocean northeast of New Zealand's North Island, and a similar distance southwest of Tonga. The islands are part of New Zealand. They are in total are ...

Habitat and biology

''Genicanthus semicinctus'' is found at depths between . it is found on the deep outer slopes of coral and rocky reefs. It normally occurs in small groups, harems of a male and as many as 4 females. This species is a

protogynous hermaphrodite Sequential hermaphroditism (called dichogamy in botany) is a type of hermaphroditism that occurs in many fish, gastropods, and plants. Sequential hermaphroditism occurs when the individual changes its sex at some point in its life. In particular, ...

and if the male in a group disappears the dominant female will change into a male, this change takes a few weeks.

Systematics

''Genicanthus semicinctus'' was first formally described as ''Holocanthus semicinctus'' in 1900 by the British-born Australian

ichthyologist Ichthyology is the branch of zoology devoted to the study of fish, including bony fish ( Osteichthyes), cartilaginous fish (Chondrichthyes), and jawless fish (Agnatha). According to FishBase, 33,400 species of fish had been described as of Octobe ...

Edgar Ravenswood Waite (1866–1928) with the type locality given as Lord Howe Island. The specific name is a compound of ''semi'' meaning “half” and ''cinctus'' meaning “bands”.

Utilisation

''Genicanthus semicinctus'' is very rare in the

aquarium An aquarium (plural: ''aquariums'' or ''aquaria'') is a vivarium of any size having at least one transparent side in which aquatic plants or animals are kept and displayed. Fishkeepers use aquaria to keep fish, invertebrates, amphibians, aq ...

trade.

References

{{Taxonbar, from=Q1959210 Halfband angelfish Fish described in 1900