Fastest fish in the sea
The myth of the fastest of fishes
It is recognized that some fishes are very fast. Somehow the title of the fastest fish often goes to the sailfish with the argument that sailfish can swim up to 70mph. However, there is not really any evidence, or measurements, of any fish going that fast. Neither is the sailfish the rightful holder of the title of the fastest fish in the ocean.
During research of the topic, we discovered that the myth arose from a story in Country Life from 1941. There is a picture of a sailfish having pierced a boat. Even it is not a scientific paper, and all numbers are based on what people think the fishes swam, scientists has cited it as if credible ever since.
Theoretical (for the scoreboard, look at the bottom)
So one might think, what does fish swimming speeds affect anything in the human world ? — is there anybody studying it scientifically? Well, yes.
The subject is investigated by marine biologists, engineers and aerospace scientists. The latter has determined a threshold for cavitation, a speed at which the skin and fins will start taking damage. The damage will happen around 15m/s, or 33 mph, or 54 km/h — only half of the reported swimming speeds in popular science.
Another issue, is the size of the fish: Larger fish are faster than smaller fish. The speed is increasing approximately linear with size up until the 15m/s. Thus a sailfish of 0.5 meter, cannot swim as fast as of 2 meters. Although their maximum speeds are probably slower than anticipated, the speeds are significantly higher than those of their prey (as the prey are smaller…).
What are then the difference between species.If there is an upper limit, what other advantages can fishes evolve?
Tuna for example, can maintain higher sustained swimming speed — I always think of them as special forces soldiers always running around. Sailfish, are specialized in that they can turn really well given their size, and their sail and fins can anchor them when they whack their bill at smaller prey. Eels, even they are long, they are not fast, but really good at sharp turns, but more importantly, really good at hiding in crevices. Flatfishes, actually utilize their shape and fly like frisbees (without rotating 😂).
Measurements
I have compiled a table of actual measurements of fish swimming speeds.
As of june 2021: The title of the fastest fish, based on measurements, goes to the Bluefin Tuna, with a maximum swimming speed of 33 mph, 54 km/h or 15m/s. Note that the speed the Tuna has recorded, is equal to the theoretical maximum. Thus, find a sufficiently large shark or other fish (Swordfish maybe ?), and they would likely be able to sprint at 33mph as well.
It is worth noting, that the values presented are sprinting. Thus they cannot be maintained for long, think about yourself or an olympic athlete, sprinting is only done for seconds at a time.
References
Svendsen MBS, Domenici P, Marras S, Krause J, Boswell KM, Rodriguez-Pinto I, m.fl. Maximum swimming speeds of sailfish and three other large marine predatory fish species based on muscle contraction time and stride length: A myth revisited. Biology Open. 1. januar 2016;bio.019919.
Iosilevskii G, Weihs D. Speed limits on swimming of fishes and cetaceans. J R Soc Interface. 3. juni 2008;5(20):329–38.
Videler JJ, Wardle CS. Fish swimming stride by stride: speed limits and endurance. Rev Fish Biol Fisheries. september 1991;1(1):23–40
Lane, F. W.(1941). How fast do fish swim?Country Life (London)90, 534–535.
