Distinctive Characters: Dorsal fin with 11 spines and 24-27 rays. Anal fin with 3 spines and 17-19 rays. Pectoral fin with 15-18 rays. Body depth 1.2-1.4 in standard length. The fourth dorsal spine extremely elongate. Large adults with a short stout spine in front of each eye.
Colour: White with two diagonal stripes. Dorsal, caudal and pectoral fins yellow. Anal spines black. Habitat and Biology: Usually found solitary or in pairs near the bottom. Feeds on zooplankton and benthic invertebrates.
Distribution: Indo-West Pacific.
Remarks: Heniochus acuminatus is very difficult to differentiate from H. diphreutes (next page). Dead specimens can be identified by counting the dorsal spines (11 in H. acuminatus, 12 in H. diphreutes). Living specimens might be distinguished by snout shape, and fin patterns or habits (see overleaf).