Sailfish

Sailfishes (genus Istiophorus) are fish living in all the oceans of the world. They are blue to gray in color and have a characteristic sail (dorsal fin) on top, which often stretches the entire length of the back. Another notable characteristic is the elongated bill, resembling that of a swordfish.

All species grow quickly, reaching 1.2 to 1.5 meters in length in a single year, and feed on the surface or at mid-depths on smaller pelagic fishes and squid.   Individuals have been clocked at speeds of up to 68.5 mph, making them the fastest fish in the ocean. Generally, do not grow to more than 10 feet in length and rarely weigh over 200 pounds, although larger specimens have been seen off the shores of Costa Rica.

The sail is normally kept folded down and to the side when swimming, but it may be raised when the feels threatened or excited, making it appear much larger than it actually is. This tactic has also been observed during feeding, when a group of use their sails to "herd" a school of fish or squid.