Watch an international swimming competition on TV and you'll be amazed at how quickly athletes can propel themselves through the water. But then, put them in a race next to a fish and their 5 or 6mph will seem like a snail's pace.
The speed at which a fish swims is determined by a host of factors: their body shape and length, tail and fin shape, their muscle, skin and scale make up, and the conditions of the water they're swimming in.
The fastest swimmers tend to have long, streamlined bodies, big and powerful tails and a pointed snout.
What's the fastest fish?
At a fishing event in Florida in the early 1900s, a hooked Indo-Pacific sailfish reportedly pulled out 91m of line in three seconds, which equates to a speed of 110kph (68mph).
This record has been questioned on the basis of both the reliability of the measurement and the laws of physics.
However, more recently, tagged sailfish have been logged accelerating at a rate that, if sustained for just two seconds, would result in a speed of 126kph (78mph). Bluefin tuna, though, can accelerate even faster – over the same two seconds, they could theoretically reach 232kph (144mph).
More fascinating fish facts
- How long can a fish live out of water?
- How do 'flying fish' fly?
- Weirdest fish: 12 of the strangest fish in the world
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