Pycnochromis nigrurus

Blacktail chromis | Chromis nigrura
Pycnochromis nigrurus
Pycnochromis nigrurus, adult, Photo: Rick Stuart-Smith


Tropical Indo-Pacific


Lines of blue spots along a brown body, blue anal fin, blue margin on dorsal fin and a yellow tail. Very similar to C. vanderbilti and C. lineata, but lacking tiny golden spot below rear dorsal fin base, and confined to Indian Ocean. An Indian Ocean species, in Australia only found at Christmas Island.


Max Size: N/A cm

Sea Temperature Range: 25.9-30.4°C

Depth: 1-30m

Habitat Generalization Index: N/A

Also referred to as the SGI (Species Generalisation Index), this describes the habitat niche breadth of the species. Species with values less than 15 are found in a relatively narrow range of reef habitat types (specialists), while those over 25 may be found on most hard substrates within their range (generalists). Learn more here.

Conservation and Rarity

IUCN Status: Not Evaluated

Occurrence: Common (47.1% of sites)

Occurrence describes how often the species is found on surveys within its distribution. It is calculated as the % of reef sites surveyed by RLS divers across all the ecoregions in which the species has been observed

Abundance: Large aggregations (237 per transect)

Abundance is calculated as the average number of individuals recorded per RLS transect, where present.