Appearance
Pomacanthus asfur has a completely different colour and pattern as a juvenile from that of the adult. Juveniles have a blue body which is marked with pale-blue and white stripes. As they mature they develop yellow markings on their dorsal and caudal fins. Until as fully mature adults they have an overall dark blue body with a blackish face, a yellow caudal fin and a broad crescent-shaped yellow band running vertically across the flanks. The dorsal fin has 12 spines and 19–20 soft rays while the anal fin has 3 spines and 19–20 soft rays, the pectoral fins each contain 17 or 18 rays. This species attains a maximum total length of 40 cm (16 in).

