Circumtropical in tropical seas. Western Atlantic: Nova Scotia, Canada to Argentina. Eastern Atlantic: British Isles (rare vagrant) and Bay of Biscay to Angola, including the Mediterranean and Canary Islands. Eastern Pacific: Vancouver Island (British Columbia, Canada) to the Galapagos Islands. Common throughout the Indian Ocean.

Body elongate, slender, and not strongly compressed; posterior end of upper jaw located at anterior rim of eye; dorsal fin with 4 or 5 spines followed by another spine and 25 to 29 soft rays (IV-V+I 25-29); lateral line without scutes; caudal peduncle with well developed fleshy keels and with dorsal and ventral peduncular fossae. Body dark to pale bluish, with 6-7 broad, dark bars; white tips on caudal lobes and on second dorsal and anal lobes.

Oceanic species with a semi-obligate commensal relationship with sharks, rays, other bony fishes and turtles. Young are usually associated with jellyfish and drifting seaweed.