What is the fastest fish?

Most sources believe that the fastest species of fish is the Indo-Pacific Sailfish, Istiophorus platypterus. According to Johnson and Gill (see below) the species has been clocked in excess of 110 km/h (68 mph) over short periods.

The Indo-Pacific Sailfish grows to over 3.4 m in total length and 100 kg in weight.  It is dark blue above, brownish laterally and silvery below. There are about twenty bars on sides of the body that are made up of bright blue spots.

The Indo-Pacific Sailfish is an oceanic species that feeds on schooling fishes such as sardines, anchovies and mackerels. Nakamura (1985) states that the feeding behaviour of I. platypterus has been observed by fishermen as follows: "when one or several sailfish found a school of prey fishes, they began to pursue it at about half speed with their fins half-folded back into the grooves. They then drove at the prey at full speed with their fins completely folded back and once they had caught up with it, they suddenly made sharp turns with their fins fully expanded to confront a part of the school and then hit the prey with the bill. Subsequently they ate the killed and stunned fish, usually head first."

Another fast-swimming group of fishes are the Mako Sharks. These fishes are sometimes seen making spectacular leaps up to 6 m out of the water. It has been calculated that for the fish to leap to this height it must have been swimming at 35.2 km/h.

Further reading

1. Johnson, G.D. & A.C. Gill in Paxton, J.R. & W.N. Eschmeyer (Eds). 1994. Encyclopedia of Fishes. Sydney: New South Wales University Press; San Diego: Academic Press [1995]. Pp. 240.
2. Nakamura, I. 1985. FAO species catalogue. Vol. 5. Billfishes of the world. An annotated and illustrated catalogue of marlins, sailfishes, spearfishes and swordfishes known to date. FAO Fish. Synop. No. 125 (5): i-iv, 1-65.
3. Springer, V.G. & J.P. Gold. 1989. Sharks in Question: The Smithsonian Answer Book. Smithsonian Institution. Pp. 187.