The species can be recognised by its distinctive colouration. It is yellowish to greyish above and white below. There are four blue bars over the eyes, a yellow line extending back from the mouth, a dark band on the caudal peduncle, a large black area above the anus and a curved band on the rear of the body.
The Halfmoon Triggerfish occurs widely across the tropical Pacific. In Australia the species is 'officially' known from the Great Barrier Reef, Queensland south to northern New South Wales. Juveniles are found further south. The fish in the image was observed well south of the recognised distribution of the species.
- Hoese, D.F., Bray, D.J., Paxton, J.R. & G.R. Allen. 2006. Fishes. In Beesley, P.L. & A. Wells. (eds) Zoological Catalogue of Australia. Volume 35. ABRS & CSIRO Publishing: Australia. parts 1-3, pages 1-2178.
- Randall, J.E., Allen, G.R. & R.C. Steene. 1997. Fishes of the Great Barrier Reef and Coral Sea. Crawford House Press. Pp. 557.