Blueblotch butterflyfish (Chaetodon plebeius)

Classification (WoRMS)

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

Accepted name: Chaetodon plebeius · Authority: Cuvier, 1831 · Taxonomic status: accepted · AphiaID: 273354.

Synonyms and superseded combinations recorded for this taxon: Chaetodon cordiformis Thiollière, 1857; Chaetodon plebelus Cuvier, 1831; Megaprotodon maculiceps Ogilby, 1910; Megaprotodon plebeius (Cuvier, 1831).

Source: World Register of Marine Species (WoRMS) — https://www.marinespecies.org/aphia.php?p=taxdetails&id=273354 (CC BY 4.0). Accessed 2026-09-25.

Biology and life history (FishBase)

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

Maximum length: 15 cm · Habitat zone: reef-associated · Body shape: short and / or deep · Vulnerability index: 10 of 100 · Fishery importance: minor commercial · Aquarium trade: commercial.

FishBase notes: Feed mainly on polyps of Acropora corals in lagoons and outer reefs. Oviparous (Ref. 205), monogamous (Ref. 52884). Form pairs during breeding (Ref. 205). Clean parasites from other fishes (Ref. 9710).

Source: FishBase species summary (SpecCode 6613) — https://www.fishbase.se/summary/Chaetodon-plebeius.html (CC BY-NC 3.0 — non-commercial use only). Accessed 2026-09-25.

Distribution and occurrence records (GBIF)

6,110 georeferenced occurrence records for Chaetodon plebeius are published through GBIF from 22 countries or marine areas. The map above plots 188 distinct locations from a sample of 3,000 records, omitting 19 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: Australia (4,768); New Caledonia (669); Fiji (198); Tonga (176); Norfolk Island (132).

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

Source: GBIF Occurrence Search (taxonKey 2385583) — https://www.gbif.org/occurrence/search?taxon_key=2385583&has_coordinate=true (records CC0 / CC BY); WoRMS distribution records (MarineRegions) — https://www.marinespecies.org/aphia.php?p=taxdetails&id=273354 (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 plebeius Cuvier, 1831 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 165657) — https://www.iucnredlist.org/species/165657/0; GBIF IUCN Red List category endpoint (taxonKey 2385583) — https://api.gbif.org/v1/species/2385583/iucnRedListCategory. Accessed 2026-09-25.

Description and natural history (Wikipedia)

It has a bright yellow body which is marked with a large horizontal, elongated blue patch on the flanks above the midline. There is a black spot with bluish white margins on the caudal peduncle and a vertical black band which also has bluish white margins running through the eye. The dorsal, anal, pelvic and caudal fins are brilliant yellow.

The juveniles lack the blue patch on the flanks. The dorsal fin contains 13-15 spines and 16-18 soft rays while the anal fin has 4-5 spines and 14-16 soft rays. This species attains a maximum total length of 15 cm.

Distribution

The blueblotch butterflyfish is found in the western Pacific Ocean and the eastern Indian Ocean. It ranges from Vietnam east to Fiji, north to southern Japan and south to Australia.

It is largely absent from Indonesia except from northern Papua. In Australia this species is found from Rottnest Island in Western Australia north to the Dampier Archipelago, it is then found from the northern Great Barrier Reef south as far as Arrawarra Headland near Coffs Harbour in New South Wales. It can also be found on the Coral Sea reefs, Elizabeth Reef, Middleton Reef and Lord Howe Island in the Tasman Sea.

Habitat and biology

Blueblotch butterflyfishes are found in a range of coral reef habitats, from lagoon shallows to the outer reef slopes. It can be found as lone individuals or as pairs. The adults are obligate corallivores, feeding mostly on the polyps of corals of the genus Pocillopora.

The juveniles have been recorded acting as cleaner fish removing ectoparasites from other fish species. The adults have also been known to feed on Acropora corals and a small amount of filamentous green algae. It occurs down to depths of 14 m.

Systematics

Chaetodon plebeius was first formally described in 1831 by the French naturalist Georges Cuvier (1769-1832) with the type locality given as "South Seas". Like the other butterflyfishes which have angular yellow bodies with black eyestripes and a single differently-colored patch, C. plebeius belongs in the subgenus Tetrachaetodon. Among this group it seems to be the most basal living species. If Chaetodon is split up, this subgenus would be placed in Megaprotodon.

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