King demoiselle (Chrysiptera rex) care guide

Group
Marine fish
Other names
Pink demoiselle, King damselfish, Rex damsel, Peach damsel, Pink damselfish, Greyhead damselfish, Yellowback damselfish
Family
Pomacentridae (damselfishes)
Origin
Eastern Indian Ocean and western Pacific; coastal to outer reef crests at 1–20 m, favouring sheltered reefs with sand and coral patches.
Water
saltwater
Maximum size
7 cm
Temperature
23–28°C
pH
8–8.5
Hardness
Salinity SG 1.020–1.026
Minimum tank
114 litres
Care level
beginner
Temperament
peaceful
Reef safe
yes

Care

Tank: a reef aquarium with moderate lighting and hiding places. The species article gives a minimum of about 114 litres (30 US gallons), and 190 litres (50 US gallons) or more for one male with several females. Water: the article recommends 23–28 °C, specific gravity 1.020–1.026 and pH 8.0–8.5. Behaviour: generally docile, but can be territorial in confined spaces and may harass smaller fish; slightly more aggressive tankmates may pick on it. Identification: pinkish-blue body with a yellow back and tail, often with a dark spot at the rear of the dorsal fin. Up to about 7 cm. Trade: regarded as beginner-friendly and reef safe. IUCN: Least Concern. Not CITES-listed. Sources: Wikipedia, List of marine aquarium fish species (en.wikipedia.org/wiki/Listofmarineaquariumfishspecies); Wikipedia (en.wikipedia.org/wiki/Chrysipterarex). Checked October 2026.

Diet

Omnivorous, mainly algae plus bottom-living invertebrates and plankton. In aquaria it accepts meaty frozen foods and plant-based foods such as spirulina and nori.

Breeding

An egg-layer with distinct pair bonds. Eggs stick to the substrate and the male guards and aerates them.

Compatibility and tank mates

Reef safe. Peaceful for a damsel: keep one male with one female in smaller tanks. Avoid much more aggressive damsels.

Last updated 8 October 2026. Community-edited care guide on Aquatic-Auctions.

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