- whale shark Rhincodon typus
- 21.5 tonne(s)/metric ton(s)
- Pakistan ()
The heaviest species of fish alive today is the whale shark Rhincodon typus. The largest scientifically recorded specimen weighed an estimated 21.5 tonnes (47,000 lb). It measured 12.65 m (41 ft 6 in) long and was 7 m (23 ft) round the thickest part of the body. This immense individual was captured off Baba Island, near Karachi, Pakistan, on 11 November 1949. There are a number of reports on file of even bigger specimens, but none of these has ever been officially confirmed.
The only creatures alive today that are heavier than the whale shark are certain giant species of whale, such as the blue whale. However, the basking shark Cetorhinus maximus comes a close second to the whale shark among fishes in terms of weight, as some specimens have been estimated to weigh as much as 19 tonnes. Thankfully, however, both of these huge shark species are entirely harmless to humans, because they are exclusively planktivorous, not carnivorous.