Japanese butterflyfish (Chaetodon nippon)

Classification (WoRMS)

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

Accepted name: Chaetodon nippon · Authority: Steindachner & Döderlein, 1883 · Taxonomic status: accepted · AphiaID: 273351.

Synonyms and superseded combinations recorded for this taxon: Chaetodon carens Seale, 1910; Chaetodon decipiens Ahl, 1923.

Source: World Register of Marine Species (WoRMS) — https://www.marinespecies.org/aphia.php?p=taxdetails&id=273351 (CC BY 4.0). Accessed 2026-09-23.

Biology and life history (FishBase)

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

Maximum length: 15 cm · Depth range: 5–30 m · Habitat zone: reef-associated · Body shape: short and / or deep · Vulnerability index: 10 of 100 · Fishery importance: minor commercial · Aquarium trade: commercial.

FishBase notes: Found in shallow rocky reefs. Spawning occurs in groups at sunset when water temperature is 23°C (Ref. 9710). Oviparous (Ref. 205). Form pairs during breeding (Ref. 205).

Source: FishBase species summary (SpecCode 12532) — https://www.fishbase.se/summary/Chaetodon-nippon.html (CC BY-NC 3.0 — non-commercial use only). Accessed 2026-09-23.

Distribution and occurrence records (GBIF)

57 georeferenced occurrence records for Chaetodon nippon are published through GBIF from 3 countries or marine areas. The map above plots 18 distinct locations from a sample of 57 records, omitting 4 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: Japan (50); Chinese Taipei (6); Philippines (1).

Source: GBIF Occurrence Search (taxonKey 2385521) — https://www.gbif.org/occurrence/search?taxon_key=2385521&has_coordinate=true (records CC0 / CC BY); WoRMS distribution records (MarineRegions) — https://www.marinespecies.org/aphia.php?p=taxdetails&id=273351 (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 nippon Steindachner & Döderlein, 1883 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 165636) — https://www.iucnredlist.org/species/165636/0; GBIF IUCN Red List category endpoint (taxonKey 2385521) — https://api.gbif.org/v1/species/2385521/iucnRedListCategory. Accessed 2026-09-23.

Description and natural history (Wikipedia)

The Japanese butterflyfish is a deep-bodied, vertically flattened fish up to 15 cm long. The dorsal fin has 12 or 13 spines and 18 to 20 soft rays while the anal fin has 3 spines and 15 or 16 soft rays. The body is creamy-brown, rimmed with dark brown. The juvenile fish has an eyespot in the region of its soft dorsal fin, but this fades as it grows.

The Japanese butterflyfish is native to the northwestern Pacific Ocean, where it occurs in the waters of Japan, South Korea, the Philippines, and Taiwan. It is particularly common around the Izu Islands. With a preference for rocky coastal reef habitats, it has been recorded at depths of between 5 and 20 m, although it is probable that it also inhabits deeper water.

The Japanese butterflyfish is a benthic fish with an omnivorous diet, which includes polychaete worms, crabs and other small invertebrates. It often moves around in large or small groups.

Although many butterflyfish form aggregations when spawning, the Japanese butterflyfish have been observed spawning in pairs. This is one of the few species of butterflyfish whose larval development has been studied. On hatching, the larvae float upside down near the surface, but at 72 hours start swimming and feed on such zooplankton as oyster larvae. By the time they are ready to settle, the butterflyfish larvae are attracted to lights at night, and at this time, their colouring transforms into that of juvenile fish with great rapidity.

This fish has a fairly wide distribution and is a common species, particularly in the Izu Islands. It seldom appears in the aquarium trade and its population seems stable, so the International Union for Conservation of Nature has assessed its conservation status as being of "least concern".

Source: Wikipedia: Chaetodon nippon — https://en.wikipedia.org/wiki/Chaetodon_nippon (CC BY-SA 4.0). Accessed 2026-09-23.