Bluestriped butterflyfish (Chaetodon fremblii)

Classification (WoRMS)

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

Accepted name: Chaetodon fremblii · Authority: Bennett, 1828 · Taxonomic status: accepted · AphiaID: 273339.

Source: World Register of Marine Species (WoRMS) — https://www.marinespecies.org/aphia.php?p=taxdetails&id=273339 (CC BY 4.0). Accessed 2026-09-23.

Biology and life history (FishBase)

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

Maximum length: 13 cm · Depth range: 4–65 m · Habitat zone: reef-associated · Body shape: short and / or deep · Vulnerability index: 10 of 100 · Fishery importance: commercial · Aquarium trade: commercial.

FishBase notes: Inhabit areas with rock or coral (Ref. 9710). Benthopelagic (Ref. 58302). Prey on the tentacles of tubeworms and other invertebrates (Ref. 3921). Oviparous (Ref. 205). Form pairs during breeding (Ref. 205).

Source: FishBase species summary (SpecCode 7808) — https://www.fishbase.se/summary/Chaetodon-fremblii.html (CC BY-NC 3.0 — non-commercial use only). Accessed 2026-09-23.

Distribution and occurrence records (GBIF)

2,876 georeferenced occurrence records for Chaetodon fremblii are published through GBIF from 3 countries or marine areas. The map above plots 32 distinct locations from a sample of 2,876 records, omitting 13 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: United States of America (2,622); United States Minor Outlying Islands (253); Australia (1).

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

Source: GBIF Occurrence Search (taxonKey 2385500) — https://www.gbif.org/occurrence/search?taxon_key=2385500&has_coordinate=true (records CC0 / CC BY); WoRMS distribution records (MarineRegions) — https://www.marinespecies.org/aphia.php?p=taxdetails&id=273339 (CC BY 4.0); Natural Earth 110m basemap — https://www.naturalearthdata.com/ (public domain). Accessed 2026-09-23.

Conservation status (IUCN Red List)

The IUCN Red List assesses Chaetodon fremblii Bennett, 1828 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 165662) — https://www.iucnredlist.org/species/165662/0; GBIF IUCN Red List category endpoint (taxonKey 2385500) — https://api.gbif.org/v1/species/2385500/iucnRedListCategory. Accessed 2026-09-23.

Description and natural history (Wikipedia)

The bluestripe butterflyfish, like other butterflyfish, are laterally flattened fish up to 15 cm long with pointed snouts and rectangular bodies. The dorsal fin has 12 to 14 spines and 20 to 21 soft rays, while the anal fin has 3 spines and 16 to 18 soft rays. The bluestripe butterflyfish has eight distinctive diagonal blue stripes radiating from the eye region, on a yellow background. There is a black spot at the top of the head and another larger spot of black at the base of the tail. This latter dark patch may serve to distract predators by encouraging them to attack the tail rather than the head end.

The bluestripe butterflyfish is endemic to the Hawaiian Islands where it is described as being abundant on coral and rocky reefs down to depths of about 28 m.

The bluestripe butterflyfish is an omnivore, unlike some butterflyfishes which feed almost exclusively on corals. These specialists usually have mating systems involving a pair bond, but the omnivorous bluestripe butterflyfish lives in a more resource-rich environment, where it is easier to find sufficient food. As a result, males of this species operate a harem system, defending a territory which includes up to four smaller female territories.

The bluestripe butterflyfish was first formally described in 1828 by the English naturalist Edward Turner Bennett (1797-1836). The specific name honours Lieutenant John Frembly R.N., a marine surveyor and geologist, who presented a collection of fish specimens from the Sandwich Islands to the Zoological Society of London.

The bluestripe butterflyfish is sometimes kept in reef aquaria where its generalised diet means that it is easier to maintain than corallivorous types. Specimens are harvested from the wild and it is sometimes difficult to get the fish to eat in captivity. In this respect, juveniles within two or three months of settling are more willing to accept prepared and novel foods. Attempts have been made to breed the fish in captivity, but the lengthy larval period of about two months in the open ocean is difficult to replicate in captivity.

Source: Wikipedia: Bluestripe butterflyfish — https://en.wikipedia.org/wiki/Bluestripe_butterflyfish (CC BY-SA 4.0). Accessed 2026-09-23.