Which fish is the largest in the world?

Is the whale shark a fish? Yes, it is a cartilaginous fish, the only member of the Rhincodontidae family. It is the largest fish in the world, ranging in size from 5 to 12 metres, and sometimes reaching 15 - 18 metres - that's more than the length of a bus!

This pelagic selachian, which can live up to 80 years, is a placid animal. It moves slowly and is harmless to humans. 

A record-breaking fish, it can filter up to 6,000 litres of water an hour and swallow a tonne of food a day. This is hardly surprising given that the whale shark can weigh up to 30 tonnes!

A large pelagic fish, the whale shark Rhincodon typus is found in all tropical, temperate and warm seas except the Mediterranean. It lives in the Atlantic Ocean, from New York to Brazil and from Senegal to the Gulf of Guinea, in a large part of the Indian Ocean and also in the Pacific Ocean.

It is often accompanied by tuna and mackerel, other pelagic fish with which it undertakes long migrations. 

It moves between the surface and a depth of 120 m, but can also dive to a depth of 1,000 m. It can be found in lagoons, near estuaries or river mouths at times when fish and invertebrates proliferate, providing the basis of its diet. 

The whale shark can be recognised by its massive body marked by three large transverse lines and five vertical gill slits located above the pectoral fins. These gills allow the shark to breathe but also filter the water it absorbs in large quantities when it eats.

Its back is a bluish-grey colour. It is dotted with white dots and lines forming a checkerboard pattern, while its belly is a light, solid colour. This distribution of dots and lines helps to identify sharks: each coat is unique. 

This shark can also be recognised by its flat head and large mouth, which varies in width from 1.50 m to 2 m.

Although it is the largest fish in the world, it is smaller than the blue whale, which at 25 metres is the largest mammal in the animal kingdom!

Sunfish are the heaviest bony fish, weighing in at 2 tonnes and measuring 2 to 3 metres in length.

The whale shark remains a mysterious animal, and little is known about its reproduction. We don't know where they mate, or where the females give birth. Nor do we know how long their gestation period lasts, although some suggest that they reproduce every two years.

The mode of reproduction is thought to be ovoviviparous, meaning that the eggs develop and hatch in the female's belly and she expels viable baby sharks. Sexual maturity is reached when the shark is 9 m long, at around 20 or 30 years of age.