Description:

Dorsal spines 9; dorsal rays 10; anal spines 3, anal rays 9.

A large full-bodied parrotfish. Dorsal profile of head steep and smoothly convex. Teeth fused to form relatively smooth dental plates. Plates broadly exposed. 
Large adults with 1 or 2 canine teeth on side at rear of upper dental plates. 3 rows of scales on cheek. Caudal fin of adults lunate.

Initial phase: body pale red to deep rich red with slight yellowish colouration dorsally in some specimens. Edge of lips with a broad blue-green band. 
Orbit rimmed with intermittent blue band. Dorsal fin pink to pale red edged in blue and with narrow blue base. Pectoral fin red some specimens exhibit 
blue anterior edge and/or 2-3 blue lines on rays. Pelvic fins red. Anal fin pinkish blue edged in blue. Caudal fin yellow with blue dorsal and ventral 
edges, and blue terminal crescent. 

Terminal Phase: body bluish-green, the scales with a vertical lavender-pink bar, shading to grey dorsoanteriorly and to purplish-blue on the snout. 
Shading ventrally to light green. Large yellow patch on cheek often becoming pink posteriorly. Broad green band of upper lip continuing diffusely to eye;
3 narrow green bands diverging posteriorly from eye. Dorsal fin intricately coloured with significant variation between individuals. Typically orange 
edged in blue, with a middle green strip and green base. The middle stripe may on occasion be blue and may also zig-zag. The orange sections may include 
blue or green spots which may merge with the bisecting green/blue line to produce a convoluted pattern on the orange background. The anal fin is similar 
with a background colour of orange with blue edge and bisected by a blue-green stripe. There may be lines blue-green spots (often laterally elongated) 
in the orange sections above and below the blue stripe. The base of the anal fin also exhibits blue spots which may merge to form a blue line. 

Maturity: Lm unknown. Range unknown. Max Length: 70 cm TL.

The maximum size recorded by Choat in Seychelles was, in 2009, 45cm TL. Significantly larger specimens are regularly seen at the Victoria Market (pers obs).

Inhabits lagoon, seaward reefs and outer flats (depth 2-35 m). Juveniles usually solitary; adults may form schools. Feeds on algae.

This species is not protected or subject to fishery regulations. It is caught in the fish trap fishery, but is an uncommon component of the catch. It is 
also targeted by illegal spear fishing activity.
 

C. strongylocephalus forms part of a species complex being replaced by C. gibbus in the Red sea and C. macrorhinos in the west Pacific.
 

Bray, D.J.  Chlorurus strongylocephalus in Fishes of Australia, http://fishesofaustralia.net.au/home/species/4936 (12/03/19). 
Choat, J.H. et al. (2012). Chlorurus strongylocephalus. The IUCN Red List 2012: http://dx.doi.org/10.2305/IUCN.UK.2012.RLTS.T190742A17787219.en. (12/03/19).
Kimura et al. (2019). Fishes of the Andaman sea. Chlorurus strongylocephalus. https://www.kahaku.go.jp/research/db/zoology/Fishes_of_Andaman_Sea/contents/scaridae/06.html (18/03/19).
Froese, R. & D. Pauly. (Eds.) (2019). FishBase. https://www.fishbase.se/summary/Chlorurus-strongylocephalus.html  (12/03/19).

Nevill, J.E.G. (2019). Chlorurus strongylocephalus, Steephead parrotfish. Seychelles Seatizens. www.seatizens.sc. https://seatizens.sc/species/chlorurus-strongylocephalus-bleeker-1855/ (edited 14/08/22).