What is the fastest fish in the sea?

The fastest fish in the sea is generally considered to be the sailfish. Its scientific genus, Istiophorus, includes sleek, open-ocean predators recognized by their long bills and enormous, sail-like dorsal fins.

Sailfish hunt smaller fish and squid in tropical and temperate waters. They can raise or fold their dorsal fin while maneuvering, and their bill helps them herd or stun prey. Older references often claimed speeds of about 35 metres per second, or roughly 125 kilometres per hour, based partly on dramatic fishing-line observations.

Modern studies have produced more cautious estimates. High-speed video and biomechanical research suggest sailfish usually reach around 10–15 metres per second, with measured bursts often below the older headline figures. Black marlin and several other billfish are sometimes proposed as contenders, but their speed records are also difficult to verify. For standard trivia, sailfish remains the accepted answer.