Blue Scissortail, Assessor macneilli Whitley 1935

Other Names: Blue Assessor, Blue Devilfish, Macneill's Assessor, Squatter

A Blue Scissortail, Assessor macneilli, on Flynn Reef, Great Barrier Reef, Queensland. Source: Andrew J. Green / Reef Life Survey. License: CC by Attribution

A dark blue scissortail with a narrow pale blue margin on the dorsal, anal, and pelvic fins. Divers often see groups of scissortails swimming upside down in caves and under ledges.

Cite this page as:
Bray, D.J. 2017, Assessor macneilli in Fishes of Australia, accessed 21 Apr 2024,

Blue Scissortail, Assessor macneilli Whitley 1935

More Info


Outer barrier reefs from Cape York to at least Lady Musgrave Reef, southern Queensland; also reefs in the Coral Sea. Elsewhere, the species occurs in New Guinea and New Caledonia. May form aggregations of up 100 individuals in caves, crevices and under ledges.


Dorsal fin XI, 8-10; Anal fin III, 9-10; Pectoral fin 14-16; gill rakers on first arch (total) 23-17; tubed lateral-line scales 17-23 + 3-9.


Planktivore - feeds on small crustaceans such as copepods, ostracods and amphipods.


Males incubate the eggs in their mouths, with an incubation period of about 15-16 days. Several days prior to hatching the male's mouth is continually held open and the eggs are shifted back and forth at intervals ranging between two to eight minutes (Allen & Kuiter 1976).

Species Citation

Assessor macneilli Whitley 1935, Rec. Aust. Mus. 19(4): 231. Type locality: Hayman Island, Whitsunday Passage, QLD.


Bray, D.J. 2017


Australian Faunal Directory

Blue Scissortail, Assessor macneilli Whitley 1935


Allen, G.R. 1997. Marine Fishes of Tropical Australia and South-east Asia. Perth : Western Australian Museum 292 pp. 106 pls.

Coleman, N. 1981. Australian Sea Fishes North of 30°S. Lane Cove, NSW : Doubleday Australia Pty Ltd 297 pp.

Kuiter, R.H. 1992. Tropical Reef-Fishes of the Western Pacific, Indonesia and Adjacent Waters. Jakarta : PT Gramedia Pustaka Utama 314 pp. pls.

Kuiter, R.H. 1996. Guide to Sea Fishes of Australia. A comprehensive reference for divers and fishermen. Sydney, NSW, Australia : New Holland Publishers xvii, 434 pp.

Kuiter, R.H. 2004. Basslets, Hamlets and their relatives. A comprehensive guide to selected Serranidae and Plesiopidae. Chorleywood, UK : TMC Publishing 1, 216 pp.

Randall, J.E., Allen, G.R. & Steene, R. 1990. Fishes of the Great Barrier Reef and Coral Sea. Bathurst : Crawford House Press 507 pp. figs.

Randall, J.E., Allen, G.R. & Steene, R. 1997. Fishes of the Great Barrier Reef and Coral Sea. Bathurst : Crawford House Press 557 pp. figs.

Russell, B.C. 1983. Annotated checklist of the coral reef fishes in the Capricorn-Bunker group, Great Barrier Reef, Australia. Great Barrier Reef Marine Park Authority. Special Publication Series 1: 1-184 figs 1-2

Whitley, G.P. 1935. Studies in Ichthyology No. 9. Records of the Australian Museum 19(4): 215-250 figs 1-11 pl. 18

Whitley, G.P. 1940. Illustrations of some Australian fishes. The Australian Zoologist 9(4): 397-428 figs 1-45 pls 30-31

Quick Facts

CAAB Code:37316004

Biology:Oral egg brooder (males)

Depth:2-20 m

Fishing:Aquarium fish

Habitat:Reef associated

Max Size:6 cm TL

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Species Maps

CAAB distribution map