Fish vary greatly in size. The extant whale shark and basking shark exceed all other fish by a considerable margin in weight and length. The extinct Otodus megalodon exceeds all other fish, extant and extinct (excluding tetrapods), in size. Fish in the common usage are a paraphyletic group that describes aquatic vertebrates while excluding the tetrapods, four limbed vertebrates nested within the lobe-finned fish, which include all land vertebrates and their nearest extinct relatives. This list therefore excludes the various marine reptiles and mammals, such as the extinct ichthyosaur, plesiosaur and mosasaur reptiles (none of which are dinosaurs) and the extant sirenia and cetacea mammals (such as the marine tetrapod blue whale, generally considered to be the largest animal known to have ever lived).
Largest extant fish
Jawless fish (Agnatha) Hagfish (Myxini) Hagfish are among the most primitive extant vertebrates. There is only one order and family in this animal class. All of the 77 known species have elongated, eel-like bodies but can be distinguished by their downward-facing mouths. The largest form is the goliath hagfish (Eptatretus goliath). This species can range up to 1.28 m (4.2 ft) in length and weigh to 6.2 kg (14 lb). Lampreys (Petromyzontiformes)
Lampreys, as with the hagfish, appear eel-like in shape. They have cartilaginous skeletons and have been evolving separately from any other group for over 400 million years. They are predatory and often attach themselves to a fish or other small animal and gradually drain blood and organs. The largest species is the sea lamprey (Petromyzon marinus), which can grow to 1.2 m (3.9 ft) and weigh 2.5 kg (5.5 lb).
Armored fish (Placodermi)
The largest fish of the now-extinct class Placodermi was the giant predatory Dunkleosteus. The largest and most well-known species was D. terrelli, which grew almost 4.1 m (13.5 ft) in length Engelman (2023), using an ellipsoid volumetric method, estimated weights of 950–1,200 kilograms (2,090–2,650 lb) for typical (3.41 metres (11.2 ft) long) adult Dunkleosteus, and weights of 1,494–1,764 kilograms (3,294–3,889 lb) for the largest (4.1 metres (13.5 ft)) individual. Its filter feeding relative, Titanichthys, may have rivaled it in size. Titanichthys reached a length of 7 m (23 ft) though in older paper it was estimated at 7.5 m (25 ft). However, according to a 2023 paper, it would have been the same size as Dunkleosteus.
Cartilaginous fish (Chondrichthyes)
The cartilaginous fish are not directly related to the "bony fish," but are sometimes lumped together for simplicity in description. The largest living cartilaginous fish, of the order Orectolobiformes, is the whale shark (Rhincodon typus), of the world's tropical oceans. It is also the largest living animal that is not a cetacean and, like the largest whales, it is a docile creature that filter-feeds on tiny plankton. An average adult of this species measures 9.7 m (32 ft) long and weighs an average of 9 tonnes. The largest verified specimen was caught in 1949 off Karachi, Pakistan and was 12.7 m (42 ft) long and weighed 21.5 tonnes (21.2 long tons; 23.7 short tons). Although many are dubious, there are several reports of larger whale sharks, with reliable sources citing unverified specimens of up to 37 tonnes (36 long tons; 41 short tons) and 17 m (56 ft) or possibly up to 21.9 metres (72 ft). The extinct Megalodon is estimated to have been the largest cartilaginous fish as well as the largest fish to have ever existed. It was macropredatory feeding mainly on marine mammals. With maximum total length estimates ranging from 14.3–24.3 metres (47–80 ft).
Ground sharks (Carcharhiniformes)
The largest species of this order is the widely distributed tiger shark (Galeocerdo cuvier). Specimens have been verified to at least 5.5 m (18 ft) but even larger ones have been reported. One specimen, a gravid female caught off Australia and measuring only 5.5 m (18 ft) long, weighed an exceptional 1,524 kg (3,360 lb). A female caught in 1957 reportedly measured 7.4 m (24 ft) and weighing 3,110 kg (6,860 lb), although this very outsized shark is not known to have been confirmed. The largest of the "requiem sharks" in the family Carcharhinidae is disputed. In axial length, it seems to be the dusky shark (C. obscurus), at up to 4.2 m (14 ft) and a weight of 350 kg (770 lb). However, the bulkier bull shark (C. leucas) has been estimated to weigh about 575 kg (1,268 lb) in recent specimens that measured over 4 m (13 ft) long. The silky shark (C. falciformis) is another contender for the largest requiem shark at a maximum weight of 350 kg (770 lb) and a maximum length of around 3.5 m (11 ft). The largest hammerhead shark is the great hammerhead (Sphyrna mokarran), which can reach 6.1 m (20 ft) and weigh at least 500 kg (1,100 lb). The most species-rich shark family, the catsharks, are fairly small-bodied. The largest, the nursehound (Scyliorhinus stellaris), can grow up to 1.7 m (5.6 ft) and a weight of at least 10.8 kg (24 lb). Within the Triakidae family, also known as houndsharks, the largest is the heavily overfished school shark (Galeorhinus galeus), also known as the soupfin shark, which can reach up to 1.95 m (6.4 ft) and 45.4 kg (100 lb). Other large fish in the order are the leopard shark (Triakis semifasciata), with one specimen recorded at 2.13 m (7.0 ft) in length, and the common smoothhound (Mustelus mustelus) at 2 m (6.6 ft). Chimaeras (Chimaeriformes) These odd, often translucent cartilaginous fish are typically quite small. The largest species is the carpenter's chimaera (Chimaera lignaria) of the oceans near Australia and New Zealand. It can reach up to 1.5 m (4.9 ft) in length and weigh 15.4 kg (34 lb). Frill sharks and cow sharks (Hexanchiformes) The largest of the frill sharks and cow shark is the bluntnose sixgill shark (Hexanchus griseus). This large species typically inhabits depths greater than 90 m (300 ft), and has been recorded as deep as 1,875 m (6,152 ft). The largest specimen known (caught off Cuba) reportedly weighed 763 kg (1,682 lb) and measured 4.82 m (15.8 ft) long. Bullhead sharks (Heterodontiformes) These tropical, small sharks are noted for their broad head shape. The largest species is the Port Jackson shark (Heterodontus portusjacksoni) of Australasian waters, at up to 1.65 m (5.4 ft) long and weighing up to 20 kg (44 lb). Mackerel sharks (Lamniformes)
… excerpt ends here. Continue reading the full article.
