Assessor macneilli

Blue Scissortail | Blue Assessor | Blue Devilfish | Macneill's Assessor | Squatter
Assessor macneilli
Assessor macneilli, QLD, Australia, Photo: Rick Stuart-Smith
Assessor macneilli
Assessor macneilli, Great Barrier Reef, Cairns, Australia, Photo: Andrew Green
Assessor macneilli
Assessor macneilli, Torres Strait, Qld, Photo: Andrew Green
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Assessor macneilli
Assessor macneilli
Assessor macneilli


Tropical Indo-Pacific


Blue body and forked tail. Swims with dorsal fin raised giving a triangular profile. Similar A. flavissimusis (Yellow Scissortail) is yellow, and Pseudochromis dottybacks lack forked tail. Swims in groups upside down under ledges and in caves, belly aligned to reef surface.


Max Size: 6 cm

Sea Temperature Range: 22.4-30.4°C

Depth: 2-20m

Habitat Generalization Index: 17.74

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 (39.9% 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 (42 per transect)

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

Edit by: RD Stuart-Smith, GJ Edgar, AJ Green, IV Shaw. 2015. Tropical Marine Fishes of Australia. Reed New Holland