Their body is elongate and compressed, The upper jaw prolonged into a very long and pointed beak. It possess two dorsal fins, the first very large, tail and sail-like, hence the name, pelvic fins narrow but very long, almost reaching anal region. Their body covered with small, embedded scales with 1 or 2 blunt points, It have about 20 bluish vertical bar on it back. The belly is pale silver in colour. The membrane of first dorsal fin blue black with numerous dark spots.
Feeds mainly on fishes, crustaceans and cephalopods. It seems to spawn throughout the year in tropical and subtropical waters of the Pacific with peak spawning occurring in the respective local summer seasons. Spawning occurs with males and females swimming in pairs or with two or three males chasing a single female (probably a mating behavior). The ripe ovarian eggs are about 0.85 mm in diameter and have a single oil globule, there are no structures on the vitalize membrane and the egg is transparent.
Habitat and Distribution
These are oceanic epipelagic species usually found above the thermocline. Most densely distributed in waters close to coasts and islands. The sail fish is found in Indo-Pacific, tropical and temperate waters of western Pacific, eastern Pacific, western Indian Ocean and eastern Indian Ocean. These are highly migratory species Undergoes spawning migrations in the Pacific.