Description:

Dorsal spines: 13-14; Dorsal rays: 17-21; Anal spines: 3; Anal rays: 18-21.
Oblong, strongly laterally compressed, body. Soft dorsal and anal fin broad, extended and rounded. Cauda fin rounded. Snout angular and projects and prominently to robust, terminal mouth. Preopercle spine well developed.
Colour. Adult, dark blue body with bright yellow stripes. Electric blue edged black mask over eyes. Cheek, snout and mouth pale grey blue. Preopercular spine blue. Forehead yellow with yellow bar extending down face. Chest and rear of head black. Dorsal fin coloured as per body with white margin and soft dorsal fin with yellow sub-margin. Anal fin dark brown with parallel curving blue lines and prominent electric blue margin. Caudal fin orange-yellow. Pectoral fin with dark rays and translucent membranes. Pelvic fins long orange-yellow with blue edge. Juveniles less than 14 cm with blue and white stripes on head and body forming concentric circles posteriorly, and a white margin on the dorsal fin.
 

Maturity: Lm unknown. Range unknown. Max Length: 40cm SL. 

Inhabits a variety of habitats (depth 1-100m, typically 2-70m) from coastal and outer reefs, deep lagoons, often in areas of rich coral growth. It is commonly seen near ledges and caves. Juveniles usually occur under ledges or in holes on shallow reefs. Feeds mainly on sponges and tunicates. Adults solitary or in pairs. Males territorial.

This species is not protected or subject to fishery regulations. It is caught in the fish trap fishery, it is an occasional but not abundant component of the catch. 

Bray, D.J. Pomacanthus imperator in Fishes of Australia, http://fishesofaustralia.net.au/home/species/653 (29/06/19).

Froese, R. & D. Pauly. Eds. 2019. https://www.fishbase.se/summary/Pomacanthus-imperator (29/06/19).

Heemstra, P. & Heemstra, E. (2004). Coastal Fishes of Southern Africa. NISC SAIAB. ISBN: 1-920033-01-7.

Pyle, R. et al 2010. Pomacanthus imperator. The IUCN Red List 2010: e.T165862A6151184. http://dx.doi.org/10.2305/IUCN.UK.2010-4.RLTS.T165862A6151184.en. (29/06/19).