King demoiselle (Chrysiptera rex)

Classification (WoRMS)

Full classification as recorded by WoRMS: Kingdom: Animalia · Phylum: Chordata · Class: Teleostei · Order: Ovalentaria incertae sedis · Family: Pomacentridae · Genus: Chrysiptera.

Accepted name: Chrysiptera rex · Authority: (Snyder, 1909) · Taxonomic status: accepted · AphiaID: 276839.

Synonyms and superseded combinations recorded for this taxon: Abudefduf rex Snyder, 1909; Glyphididontops rex (Snyder, 1909); Glyphidodontops rex (Snyder, 1909).

Source: World Register of Marine Species (WoRMS) — https://www.marinespecies.org/aphia.php?p=taxdetails&id=276839 (CC BY 4.0). Accessed 2026-09-25.

Biology and life history (FishBase)

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

Maximum length: 7 cm · Depth range: 1–20 m · Habitat zone: reef-associated · Body shape: fusiform / normal · Vulnerability index: 10 of 100 · Fishery importance: commercial · Aquarium trade: commercial.

FishBase notes: Adults are found in 1-6 m (Ref. 7247) and in coastal to outer reef crests to depths of about 20 m (Ref. 48636). They occur solitarily or in groups in reef margins and upper seaward slopes subject to mild surge (Ref. 9710). Feed mainly on algae. Oviparous, distinct pairing during breeding (Ref. 205).

Eggs are demersal and adhere to the substrate (Ref. 205). Males guard and aerate the eggs (Ref. 205). Diurnal species (Ref. 113699).

Source: FishBase species summary (SpecCode 5699) — https://www.fishbase.se/summary/Chrysiptera-rex.html (CC BY-NC 3.0 — non-commercial use only). Accessed 2026-09-25.

Distribution and occurrence records (GBIF)

1,677 georeferenced occurrence records for Chrysiptera rex are published through GBIF from 14 countries or marine areas. The map above plots 120 distinct locations from a sample of 1,677 records, omitting 18 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 (1,405); Japan (96); Indonesia (50); Philippines (49); Palau (25).

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

Source: GBIF Occurrence Search (taxonKey 2399262) — https://www.gbif.org/occurrence/search?taxon_key=2399262&has_coordinate=true (records CC0 / CC BY); WoRMS distribution records (MarineRegions) — https://www.marinespecies.org/aphia.php?p=taxdetails&id=276839 (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 Chrysiptera rex (Snyder, 1909) 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 188481) — https://www.iucnredlist.org/species/188481/0; GBIF IUCN Red List category endpoint (taxonKey 2399262) — https://api.gbif.org/v1/species/2399262/iucnRedListCategory. Accessed 2026-09-25.

Description and natural history (Wikipedia)

This small reef fish was originally described by Snyder in 1909 as Abudefduf rex from a type specimen collected at Naha, Okinawa Island, Ryukyu Islands, Japan.

The species has been described under several scientific names:

Common Names

This species is known by numerous common names, including king demoiselle, pink demoiselle, king damselfish, pink damsel, pink damselfish, peach damsel, rex damsel, rex damselfish, greyhead damselfish, and yellowback damselfish.

The king demoiselle has several noteworthy characteristics beyond its basic taxonomy and distribution that make it particularly interesting both in the wild and in aquarium settings.

Physical Appearance and Geographic Variation

The coloration of this species varies significantly depending on geographic origin. Specimens collected from the Palau area display a whitish body with a bluish head, while individuals from other locations typically have a greyish head with the remaining body and fins appearing yellowish to pinkish-orange. This pink to apricot coloration is often accented with small purple spots and lines on the darker face. The species reaches a maximum size of 6-7 centimeters.

Habitat and Distribution

The king demoiselle inhabits coastal to outer reef crests at depths ranging from 1 to 20 meters (approximately 3 to 70 feet). It shows a preference for lagoons and sheltered reefs, particularly favoring areas with shallow sand and coral patches near reef edges, where it is abundant in northwest Australia. The species has a broad tropical Indo-Pacific distribution, ranging from the eastern Indian Ocean to the Philippines, Palau, Indonesia, New Guinea, New Britain, Solomon Islands, north to southern Japan, and south to New Caledonia and the Great Barrier Reef.

Diet and Feeding Behavior

As an omnivore with algae-grazing tendencies, the king demoiselle feeds primarily on algae along with benthic invertebrates and plankton in its natural environment. This dietary flexibility makes it relatively easy to maintain in captivity, where it readily accepts meaty foods such as mysis shrimp, brine shrimp, squid, fish flesh, clams, and plant-based foods including spirulina flakes and nori.

Unlike many damselfish species known for aggression, the king demoiselle is notably docile and peaceful. However, it can become territorial in confined spaces and may annoy smaller fishes. This species is sometimes picked on by slightly more aggressive tankmates, so aquariums should provide adequate hiding places. The fish can be kept individually or in groups, with recommendations for a single male and female in smaller aquariums or a male with several females in larger systems of 50+ gallons.

The species is oviparous with distinct pairing during breeding. Eggs are demersal, adhering to the substrate, and males take on the responsibility of guarding and aerating the eggs.

The king demoiselle is considered suitable for beginners due to its hardiness and adaptability. It is reef-safe and generally compatible with peaceful tankmates. The minimum recommended tank size is 30 gallons, with optimal water parameters including temperatures of 74-84°F (23-28°C), specific gravity of 1.020-1.026, and pH of 8.0-8.5. The species requires moderate lighting and benefits from environments with live rock, caves, and hiding places.

While not heavily studied from a conservation perspective, the species is classified as Least Concern by the IUCN. It occurs with moderate frequency, being found at approximately 10.3% of surveyed reef sites within its range, with relatively high abundance averaging 35 individuals per transect where present.

Source: Wikipedia: Chrysiptera rex — https://en.wikipedia.org/wiki/Chrysiptera_rex (CC BY-SA 4.0). Accessed 2026-09-25.