Billfishes, marlins and sailfishes are the common names for the members of the Istiophoridae family. The family members are distinguished by their upper jaw which prolonged into a long spear and round in cross-section. Their caudal fin are large and forked, with a pair of keels on either side at base, and a small shallow notch on both upper and lower profiles of caudal peduncle. Both their first dorsal fin and anal fins can be folded back into grooves.
Members of the Istiophoridae are found in the tropical and subtropical seas around the world. There are 5 genera and 11 species worldwide. In Malaysia there are 3 genera and 5 species.
Billfishes are among the largest and swiftest fishes of the oceans, mostly found near the surface of waters. They are long distance migratory fishes. They are carnivorous fish, and feed commonly on other schooling fishes, crustaceans and squids. They are excellent game fishes and frequently caught using drifting bait.