Yellowstriped cardinalfish (Ostorhinchus cyanosoma)

Classification (WoRMS)

Full classification as recorded by WoRMS: Kingdom: Animalia · Phylum: Chordata · Class: Teleostei · Order: Apogoniformes · Family: Apogonidae · Genus: Ostorhinchus.

Accepted name: Ostorhinchus cyanosoma · Authority: (Bleeker, 1853) · Taxonomic status: accepted · AphiaID: 319876.

Synonyms and superseded combinations recorded for this taxon: Apogon cyanosoma Bleeker, 1853; Apogon cyanosomus Bleeker, 1853; Ostorhynchus cyanosoma (Bleeker, 1853).

Source: World Register of Marine Species (WoRMS) — https://www.marinespecies.org/aphia.php?p=taxdetails&id=319876 (CC BY 4.0). Accessed 2026-09-23.

Biology and life history (FishBase)

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

Maximum length: 8 cm · Common length: 6 cm · Depth range: 1–50 m · Habitat zone: reef-associated · Body shape: fusiform / normal · Vulnerability index: 10 of 100 · Fishery importance: commercial · Aquarium trade: commercial.

FishBase notes: Inhabits sheltered clear water areas of lagoon and seaward reefs from depths of 1 to at least 49 m. Found in small or large aggregations under ledges, in holes, or even among long spines of sea urchins. Feeds on planktonic crustaceans and small invertebrates. Has been reared in captivity (Ref. 35404).

Source: FishBase species summary (SpecCode 4600) — https://www.fishbase.se/summary/Ostorhinchus-cyanosoma.html (CC BY-NC 3.0 — non-commercial use only). Accessed 2026-09-23.

Distribution and occurrence records (GBIF)

1,620 georeferenced occurrence records for Ostorhinchus cyanosoma are published through GBIF from 45 countries or marine areas. The map above plots 310 distinct locations from a sample of 1,620 records, omitting 37 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 (646); Philippines (148); Indonesia (137); Fiji (88); Tonga (84).

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

Source: GBIF Occurrence Search (taxonKey 2397348) — https://www.gbif.org/occurrence/search?taxon_key=2397348&has_coordinate=true (records CC0 / CC BY); WoRMS distribution records (MarineRegions) — https://www.marinespecies.org/aphia.php?p=taxdetails&id=319876 (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 Ostorhinchus cyanosoma Bleeker, 1853 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 193351) — https://www.iucnredlist.org/species/193351/0; GBIF IUCN Red List category endpoint (taxonKey 2397348) — https://api.gbif.org/v1/species/2397348/iucnRedListCategory. Accessed 2026-09-23.

Description and natural history (Wikipedia)

O. cyanosoma is usually a blueish silver color with orange-yellow stripes, and grows to be an average of 6 centimeters. It lives in waters up to 50m in depth, often in lagoons or coral reefs. It is active during the nighttime, feeding on small plants and animals, mostly plankton. It has been the subject of research to test what might happen to marine life by the year 2100, due to predicted carbon dioxide levels in the atmosphere.

The prolific Dutch East Indies-resident ichthyologist Pieter Bleeker first described this species in 1853 from a specimen taken at Lawajong off Solor Island in modern Indonesia's East Nusa Tenggara province. His unique, original holotype is lodged at the Naturalis Biodiversity Center in the Netherlands.

No one has described a synonymous species, so Bleeker's original species name cyanosoma remains unchallenged. However, the genus Apogon which he placed it in masked significant differences between species. More recently, on the basis of physical (2005) and genetic (2014) characteristics, it has been transferred into the genus Ostorhinchus.

On the journey to dissecting the O. cyanosoma species complex now incorporating O. cyanosoma, O. rubrimacula, O. wassinki, and O. properuptus, the last was for a while considered a synonym of O. cyanosoma.

Large examples of Ostorhinchus cyanosoma grow to 8 cm in length although its average length is 6 cm. The fish is colored silver with a blueish tinge, and has six orange-yellow stripes including a short stripe behind the eye.

A new species (Ostorhinchus rubrimacula) was separated out in 1998 from the O. cyanosoma species complex, with almost identical morphology but with a pinkish-red spot on the tail base, and the genetics were confirmed in 2014. Notably, whilst Bleeker noted red fins ('pinnis rubris') in his original sample, he never noted a red tail spot.

Using a shorthand meristics formula, O.

The most comprehensive recent authority locates O. cyanosoma ranging across the Indo-Pacific, from the Red Sea south to east Africa, east via western Australia and Queensland to New Caledonia, and north to Ryukyu and Ogasawara islands.

It lives in clear water areas of lagoons and shallow reefs, inhabiting waters from 1 to 50 meters (usually above 15m), and makes its home under ledges, in holes, and in between the spines of sea urchins.

Coral reef fish settlement tends to be dominated by larval recruitment, but in at least part of Australia's Great Barrier Reef, around one third of recruitment of O. cyanosoma at any given coral reef patch tends to be by adult and juvenile migration across intervening sand and coral debris.

Within the large aggregations in which O. cyanosoma prefers, stable male-female pairs are often found. Individuals in pairs are more likely to live in one site, and to be able to return to that site if removed (with or without their partner), than are unpaired individuals. Retaining a fixed spatial refuge on a reef may be a crucial factor in surviving the often ferocious piscivorous predation found there.

O. cyanosoma specimens have been found with gall bladder infections of Ceratomyxa cyanosomae, Ceratomyxa cardinalis, Ellipsomyxa apogoni, and Zschokkella ohlalae,. Two species have also been found in skeletal muscle cells: Kudoa cheilodipteri and Kudoa whippsi. These tiny cnidarian parasites from class Myxosporea are doubly fascinating because this group can require two intermediate hosts involving two sexual stages (an extremely rare phenomenon in the parasite world).

O. cyanosoma is mainly a nocturnal planktivore, emerging from hiding in coral caves and crevices to feed by hovering just above sandy microhabitats on coral reef flats. By defecating during the daytime in a non-feeding microhabitat, O. cyanosoma probably helps cycle reef nutrients around different communities on the reef. It appears to prefer to eat small benthic sergestid crustaceans rather than the planktonic larvae to be found higher in the water column. However, seasonal or sampling effects may play a role in defining the diet, since in certain years, certain sites appear to suggest that O. cyanosoma is actually eating significant amounts of planktonic copepods and crustacean larvae.

Source: Wikipedia: Ostorhinchus cyanosoma — https://en.wikipedia.org/wiki/Ostorhinchus_cyanosoma (CC BY-SA 4.0). Accessed 2026-09-23.