Sailfish are a
genus Istiophorus of
billfish living in warmer sections of all the oceans of the world. They are predominantly blue to gray in colour and have a characteristic erectile
dorsal fin known as a
sail, which often stretches the entire length of the back. Another notable characteristic is the elongated bill, resembling that of the
swordfish and other
marlins. They are therefore described as
billfish in sport-fishing circles.