Diagonal butterflyfish (Chaetodon fasciatus)

Classification (WoRMS)

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

Accepted name: Chaetodon fasciatus · Authority: Forsskål, 1775 · Taxonomic status: accepted · AphiaID: 218737.

Synonyms and superseded combinations recorded for this taxon: Chaetodon flavus Bloch & Schneider, 1801; Rabdophorus linophora fasciatus (Forsskål, 1775).

Source: World Register of Marine Species (WoRMS) — https://www.marinespecies.org/aphia.php?p=taxdetails&id=218737 (CC BY 4.0). Accessed 2026-09-25.

Biology and life history (FishBase)

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

Maximum length: 22 cm · Common length: 15 cm · Depth range: 2–25 m · Habitat zone: reef-associated · Body shape: short and / or deep · Vulnerability index: 14.4 of 100 · Fishery importance: commercial · Aquarium trade: commercial.

FishBase notes: Commonly found on reef flats (Ref. 9710). Usually solitary or in pairs in areas with rich coral growth. Monogamous (Ref. 52884). Feed mainly on coral polyps (Ref. 4858). Oviparous (Ref. 205). Form pairs during breeding (Ref. 205).

Source: FishBase species summary (SpecCode 12274) — https://www.fishbase.se/summary/Chaetodon-fasciatus.html (CC BY-NC 3.0 — non-commercial use only). Accessed 2026-09-25.

Distribution and occurrence records (GBIF)

1,172 georeferenced occurrence records for Chaetodon fasciatus are published through GBIF from 18 countries or marine areas. The map above plots 66 distinct locations from a sample of 1,172 records, omitting 10 inland records that carry an institution's coordinates rather than a collection site; it shows where the species has been observed and reported, not a modelled range.

Most records by country or area: Egypt (975); Saudi Arabia (68); Israel (59); Jordan (28); Philippines (10).

The full country table, WoRMS marine regions and the sampling notes are on this species' Distribution page.

Source: GBIF Occurrence Search (taxonKey 2385538) — https://www.gbif.org/occurrence/search?taxon_key=2385538&has_coordinate=true (records CC0 / CC BY); WoRMS distribution records (MarineRegions) — https://www.marinespecies.org/aphia.php?p=taxdetails&id=218737 (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 Chaetodon fasciatus Forsskål, 1775 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 165705) — https://www.iucnredlist.org/species/165705/0; GBIF IUCN Red List category endpoint (taxonKey 2385538) — https://api.gbif.org/v1/species/2385538/iucnRedListCategory. Accessed 2026-09-25.

Description and natural history (Wikipedia)

The diagonal butterflyfish has a yellow body marked with 11 diagonal stripes. On the head there is a vertical black band through the eye and an incomplete white band on the forehead. The dorsal, anal, and caudal fins are yellow. This species attains a maximum total length of 22 cm.

The diagonal butterflyfish is found in the northwestern Indian Ocean. It has been recorded from the Red Sea and the Gulf of Aden south as far as Kenya.

Diagonal butterflyfish are found over and around corals, on which they feed. They have also been observed feeding on gelatinous zooplankton, such as jellyfish (Scyphozoa) and comb jellies (Ctenophora).

The diagonal butterflyfish was first formally described in 1775 by the Swedish speaking Finnish born naturalist Peter Forsskål (1732-1763) with the type locality given as Jeddah. It belongs to the large subgenus Rabdophorus which might warrant recognition as a distinct genus. In this group, its closest relative is probably the very similar common raccoon butterflyfish (C. lunula). Other close relatives appear to be the black butterflyfish (C. flavirostris), Philippine butterflyfish (C. adiergastos), and perhaps also the unusual red-tailed butterflyfish (C. collare).

Although the coloration of this group varies quite a lot, they are all largish butterflyfishes with an oval outline, and most have a pattern of ascending oblique stripes on the flanks. Except in the red-tailed butterflyfish, there is at least a vestigial form of the "raccoon" mask, with a white space between the dark crown and eye areas.

Source: Wikipedia: Diagonal butterflyfish — https://en.wikipedia.org/wiki/Diagonal_butterflyfish (CC BY-SA 4.0). Accessed 2026-09-25.