Halfbanded angelfish (Genicanthus semicinctus)

Classification (WoRMS)

Full classification as recorded by WoRMS: Kingdom: Animalia · Phylum: Chordata · Class: Teleostei · Order: Acanthuriformes · Family: Pomacanthidae · Genus: Genicanthus.

Accepted name: Genicanthus semicinctus · Authority: (Waite, 1900) · Taxonomic status: accepted · AphiaID: 279095.

Synonyms and superseded combinations recorded for this taxon: Holacanthus semicinctus Waite, 1900.

Source: World Register of Marine Species (WoRMS) — https://www.marinespecies.org/aphia.php?p=taxdetails&id=279095 (CC BY 4.0). Accessed 2026-09-25.

Biology and life history (FishBase)

Measured values published by FishBase for Genicanthus semicinctus. Only fields the database actually holds for this species are shown; these are database values, not aquarium guidance.

Maximum length: 21 cm · Depth range: 10–100 m · Habitat zone: reef-associated · Body shape: short and / or deep · Vulnerability index: 11 of 100 · Fishery importance: commercial · Aquarium trade: commercial.

FishBase notes: Inhabits deep coral reef areas (Ref. 4759). Also found in rocky reefs. May be found in groups (Ref. 90102).

Source: FishBase species summary (SpecCode 10896) — https://www.fishbase.se/summary/Genicanthus-semicinctus.html (CC BY-NC 3.0 — non-commercial use only). Accessed 2026-09-25.

Distribution and occurrence records (GBIF)

53 georeferenced occurrence records for Genicanthus semicinctus are published through GBIF from 1 countries or marine areas. The map above plots 6 distinct locations from a sample of 53 records; it shows where the species has been observed and reported, not a modelled range.

Most records by country or area: Australia (51).

Marine regions with a valid WoRMS distribution record: New Zealand Exclusive Economic Zone.

Source: GBIF Occurrence Search (taxonKey 2396472) — https://www.gbif.org/occurrence/search?taxon_key=2396472&has_coordinate=true (records CC0 / CC BY); WoRMS distribution records (MarineRegions) — https://www.marinespecies.org/aphia.php?p=taxdetails&id=279095 (CC BY 4.0); Natural Earth 110m basemap — https://www.naturalearthdata.com/ (public domain). Accessed 2026-09-25.

Conservation status (IUCN Red List)

The IUCN Red List assesses Genicanthus semicinctus (Waite, 1900) as Least Concern (code LC). No trend, population estimate or threat analysis is given here, because none is available from this source without the Red List API; follow the source link for the full assessment, including its date.

Source: IUCN Red List of Threatened Species (taxon 165866) — https://www.iucnredlist.org/species/165866/0; GBIF IUCN Red List category endpoint (taxonKey 2396472) — https://api.gbif.org/v1/species/2396472/iucnRedListCategory. Accessed 2026-09-25.

Description and natural history (Wikipedia)

Genicanthus semicinctus like the other angelfishes in the genus Genicanthus, shows sexual dichromatism, 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 and yellow lobes with long filaments on the caudal fin 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 has 3 spines and 17 soft rays. This species attains a maximum total length of 21 cm.

Distribution

Genicanthus semicinctus is found in the southwestern Pacific Ocean. Here it is found only around Lord Howe Island, an Australian territory in the Tasman Sea, and the New Zealand outlying islands of the Kermadec Islands.

Habitat and biology

Genicanthus semicinctus is found at depths between 10 and 100 m. 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 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 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".

Genicanthus semicinctus is very rare in the aquarium trade.

Source: Wikipedia: Halfbanded angelfish — https://en.wikipedia.org/wiki/Halfbanded_angelfish (CC BY-SA 4.0). Accessed 2026-09-25.