Enneapterygius rufopileusBlack-cheek threefin | Redcap Triplefin | Enneapterygius rufopilea
Temperate Australasia, Tropical Indo-Pacific
Female mottled brown with small saddles along back. Male reddish with black head during spawning season; rear half of body often dark with two white bands. Usually narrow white or light bar at tail base. First dorsal fin is noticeably shorter than second in females (50% of height) and slightly shorter in male (75% of height).
Restricted to offshore locations such as Lord Howe and Norfolk islands. Not present on mainland Australia. NB: map and database records to be updated when resources permit.
Similar E. atrogulare (Ringscale Threefin) has comparatively longer first dorsal fin (at least 75%, but often same height as second dorsal). Easily separated by location as it is not found offshore from mainland Australia.
Males of other Enneapterygius threefins can have black heads; e.g. E. larsonae (Blackhead Threefin) and E. similis (Masked Threefin).
Max Size: 4 cm
Sea Temperature Range: 18.7-25.2°C
Habitat Generalization Index: 12.25
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 (22.8% 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: Many (26 per transect)
Abundance is calculated as the average number of individuals recorded per RLS transect, where present.
Edit by: Andrew Green