Sailfish n. : The banner fish, or spikefish (Histiophorus.)

Sailfish n. : The basking, or liver, shark.

Sailfish n. : The quillback.

Example:
Why are Sailfish the fastest fish in water?

Taxonomy
Sailfish, fish, Quepos, free encyclopedia, Istiophorus albicans, Istiophorus platypterus, sail, species of fishes, Istiophorus, characteristic, speeds, Fossil range, Indo-Pacific sailfish, Costa Rica, search, submarines, USS Sailfish, Middle Miocene.

Defination from the web:
Sailfish are two species of fishes in the genus Istiophorus, living in warmer sections of all the oceans of the world. ... This tactic has also been observed during feeding, when a group of sailfish use their sails to "herd" a school of fish or squid. ...