Lobe-finned fish (Sarcopterygii)
The largest living lobe-finned fish is the coelacanth. The average weight of the living West Indian Ocean coelacanth, (Latimeria chalumnae), is 80Â kg (176Â lb), and they can reach up to 2Â m (6.5Â ft) in length. Specimens can measure up to 110Â kg (240Â lb). The largest lobe-finned fish of all time was Hyneria at up to 5Â m (16Â ft).
The largest lungfish, the African lungfish (Protopterus aethiopicus), is smooth, elongated, and cylindrical with deeply embedded scales. The tail is very long and tapers at the end. They can reach a length of up to 2 m (6.6 ft) and may weigh as much as 50 kg (110 lb). The pectoral and pelvic fins are also very long and thin, almost spaghetti-like. The newly hatched young have branched external gills much like those of newts. After 2 to 3 months the young transform (called metamorphosis) into the adult form, losing the external gills for gill openings. These fish have a yellowish gray or pinkish toned ground color with dark slate-gray splotches, creating a marbling or leopard effect over the body and fins. The color pattern is darker along the top and lighter below.
Ray-finned bony fish (Actinopterygii)
The largest living bony fish (superclass Osteichthyes, which includes both ray-finned and lobe-finned fish) is the widely distributed ocean sunfish (Mola mola), a member of the order Tetraodontiformes. The record size sunfish crashed into a boat off Bird Island, Australia in 1910 and measured 4.3Â m (14Â ft) from fin-to-fin, 3.1Â m (10Â ft) in length and weighed about 2,300Â kg (5,100Â lb).
As to length, the longest extant bony fish on earth is the king of herrings or oarfish (Regalecus glesne). Slender and compressed, this fish averages over 6Â m (20Â ft) long at maturity. A specimen caught in 1885 of 7.6Â m (25Â ft) in length weighed 275Â kg (610Â lb). The longest known king of herrings, which was hit by a steamship, was measured as 13.7Â m (45Â ft) long, but unverified specimens have been reported up to 16.7Â m (55Â ft).
Much larger bony fish existed prehistorically, the largest ever known having been Leedsichthys, of the Jurassic period in what is now England. This species is certainly the largest bony fish ever and perhaps the largest non-cetacean marine animal to have ever existed. Estimates of the size of this fish range from 21Â m (70Â ft) to 27Â m (90Â ft) and mass from 20 to 50 tons. A maximum size of 22Â m (72Â ft) and 25â"30 tons has been deemed to be most realistic.
- Sturgeons (Acipenseriformes)
- The largest species is the beluga sturgeon (Huso huso) of the Caspian and Black seas, the only extant bony fish to rival the massiveness of the Ocean Sunfish. The largest specimen considered reliable (based on remains) was caught in Volga estuary in 1827 and measured 7.3Â m (24Â ft) and weighed 1,474Â kg (3,250Â lb). The slightly smaller Kaluga (Huso dauricus) or Great Siberian Sturgeon has been weighed reliably up to 1,140Â kg (2,500Â lb) (Berg, 1932) and a length of 5.6Â m (18.5Â ft). The North American White Sturgeon (Acipenser transmontanus), unverified to 907Â kg (2,000Â lb) and 6.1Â m (20.1Â ft), Chinese, European Oceanic, and the Russian sturgeon (A. gueldenstaedtii), at as much as 1,000Â kg (2,200Â lb) and 5.5Â m (18.2Â ft) for a 75-year-old female, also can attain great sizes. Atlantics and Baikal sturgeons are following as well. These fish are sometimes called the largest freshwater fish but sturgeons spend a great deal of time in brackish water and switch back and forth between saltwater and freshwater environments in their life cycle. Also included in this order are the paddlefish and the Chinese Paddlefish (Psephurus gladius), which may now be extinct and is at least critically endangered, is also a very large fish. Reportedly, fisherman as recently as the 1950s have caught paddlefish measuring up to 6.7Â m (22Â ft) in total length, although no specimen greater than 3.1Â m (10Â ft) has been scientifically measured. The weight of the Chinese Paddlefish is reportedly 300 to 500Â kg (660 to 1,100Â lb).
- Bonefishes (Albuliformes)
- The largest bonefishes a is Bonefish (Albula vulpes) weighs up to 19Â lb (8.6Â kg) and measures up to 90Â cm (35Â in) long. It is silvery in color with dusky fins. The bases of the pectoral fins are yellow.
- Bowfins (Amiiformes)
- The largest species bowfins Bowfin (Amia calva) The most distinctive characteristic of the bowfin is its very long dorsal fin consisting of 145 to 250 rays, and running from mid-back to the base of the tail. The caudal fin is a single lobe, though heterocercal. They can grow up to 109 centimetres (43Â in) in length, and weigh 9.75 kilograms (21.5Â lb).
- Eels (Anguilliformes)
- The largest species of "true eel", if measured in weight and overall bulk, is the European conger (Conger conger). The maximum size of this species has been reported to 3Â m (10Â ft) and a mass of 110Â kg (240Â lb). Several moray eels can equal or exceed the previous eel in length but do not weigh as much. The longest fish in the order, at up to 4Â m (13Â ft), is the Slender giant moray (Strophidon sathete) of the Indo-Pacific oceans.
- Silversides (Atheriniformes)
- An order best known for its tiny representatives, the largest species is the jacksmelt (Atherinopsis californiensis) of the Pacific Ocean. Although it reaches 45Â cm (18Â in), it is not known to even reach 450Â g (1Â lb).
- Barreleyes and Slickheads (Argentiniformes)
- The largest barreleyes are Javelin spookfish (Bathylychnops exilis)found in the northern Pacific and in the eastern Atlantic Ocean near the Azores where it is found at depths of around 640 metres (2,100Â ft). This species grows to a length of 50 centimetres (20Â in) SL.
- Jellynose fishes (Ateleopodiformes)
- The largest jellynose fishes is Ateleopus japonicus is an exception, retaining several fins as adults and having ventral fins that are located behind (not below) the pectoral fins. Dorsal fins tend to be high, with a rather short base (9-13 rays, but in some as few as three); they are placed just behind the head. They have seven branchiostegal rays. The species have a range of sizes, the longest reaching 2Â m (6.6Â ft).
- Grinners (Aulopiformes)
- The largest member of this order is the lancetfish (Alepisaurus ferox), found in all the world's oceans. Slender, with a huge spine, these fish can reach 2.1Â m (7Â ft) long and can weigh up to 11Â kg (24Â lb).
- Toadfish (Batrachoidiformes)
- The largest toadfish is the Pacuma toadfish (Batrachoides surinamensis), reaching a size of up to 5Â lb (2.3Â kg) and 23Â in (58Â cm).
- Flying-fish and allies (Beloniformes)
- The largest member of this order, best known for its members' ability to breach the water and zip through the sky, is the pelagic Houndfish (Tylosurus crocodilus), a slender fish at up to 1.5Â m (5Â ft) and a weight of 6.35Â kg (14.0Â lb). The largest true "flying fish" is the Japanese flying fish (Cheilopogon pinnatibarbatus japonicus), which can range up to 0.5Â m (1.6Â ft) in length and weigh over 1Â kg (2.2Â lb).
- Squirrelfish (Beryciformes)
- Best known for their highly poisonous barbs, the squirrelfish's largest representative is the giant squirrelfish (Sargocentron spiniferum) of the Indo-Pacific, at up to 51Â cm (20Â in) and 2.6Â kg (5.7Â lb). The slimmer Holocentrus adscensionis from warm parts of the Atlantic can reach even greater lengths of up to 61Â cm (24Â in).
- Characins (Characiformes)
- The largest species is the African freshwater fish, the Giant Tigerfish (Hydrocynus goliath). The top size of this fish is 1.5Â m (5Â ft) and 50Â kg (110Â lb). Among the largest of the characin family is the popular sport-fish, the Golden Dorado (Salminus brasiliensis), which can reach up to 1Â m (3.3Â ft) in length and weigh 31.4Â kg (69Â lb). Among the characins are the infamous neotropical piranhas. Carnivorous species can grow up to 0.43Â m (1.4Â ft), although the Tambaqui (Colossoma macropomum), at up to 1Â m (3.3Â ft) and 32.4Â kg (71Â lb), is often considered a giant, herbivorous form of piranha.
- Herring (Clupeiformes)
- The largest herring is probably the Dorab wolf herring (Chirocentrus dorab) of the Indo-Pacific oceans. The maximum size of this species has been reported as much as 1.8Â m (6Â ft), but these slender fish have never been recorded as exceeding 3.4Â kg (7.5Â lb) in weight.
- Minnows and allies (Cypriniformes)
- The minnow family (which includes carp), Cyprinidae, is the largest family of vertebrates, with over 2400 species known today. The largest species is probably the giant barb (Catlocarpio siamensis), which is endemic to three river basins in central Asia and reaches a size of as much as 3Â m (10Â ft) and a weight of as much as 300Â kg (660Â lb). In centuries past, the Mahseer (Barbus tor) of Southern Asia was reported to reach similar or even larger proportions, but these are dubious since specimens nearly as large as the giant barb have never been reported in recent centuries.
- Pikes and allies (Esociformes)
- The largest species in this small but interesting order (formerly allied with the salmonids) is the Muskellunge (Esox masquinongy) of the rivers of North America. These predatory fish can grow up to 1.8Â m (6.0Â ft) and 45.4Â kg (100Â lb).
- Killifish and allies (Cyprinodontiformes)
- The largest species in this relatively small-bodied order is the Pacific four-eyed fish (Anableps dowei), reaching a size of 34Â cm (13Â in) and 588Â g (1.3Â lb).
- Ladyfishes and allies (Elopiformes)
- This small order is usually considered closely related to the true eels although its members are very different in appearance and behavior from eels. The largest species is much-coveted-sport fish, the Atlantic tarpon (Megalops atlanticus). The maximum recorded size for this species is 161Â kg (350Â lb) and length is up to 2.5Â m (8.2Â ft).
- Cod (Gadiformes)
- The Atlantic cod (Gadus morhua) grows to 2Â m (6.7Â ft) long and 96Â kg (212Â lb).
- Sticklebacks and allies (Gasterosteiformes)
- The largest form of stickleback, a small, cylindric type of fish, is the Sea stickleback or Fifteenspine stickleback (Spinachia spinachia). This species can range up to 22Â cm (8.7Â in) in length and weigh up to 8.5Â g (0.3Â oz).
- Clingfish (Gobiesociformes)
- These bottom-dwelling fish reach their maximum size in Sicyases sanguineus. This species can reach 30Â cm (12Â in) in length and weigh up to 1Â kg (2.2Â lb).
- Shellears and allies (Gonorynchiformes)
- The well-known milkfish (Chanos chanos) is the largest member of this order. The maximum size is 22.7Â kg (50Â lb) and 1.84Â m (6.1Â ft) long.
- Knifefish (Gymnotiformes)
- The largest knifefish is the Electric eel (Electrophorus electricus) The electric eel has an elongated, cylindrical body, typically growing to about 2Â m (6Â ft 7Â in) in length, and 20Â kg (44Â lb) in weight, making it the largest species of the Gymnotiformes. The coloration is dark gray-brown on the back and yellow or orange on the belly. Mature males have a darker color on the belly. They have no scales. The mouth is square, and positioned at the end of the snout. The anal fin extends the length of the body to the tip of the tail. As in other ostariophysan fishes, the swim bladder has two chambers. The anterior chamber is connected to the inner ear by a series of small bones derived from neck vertebrae called the Weberian apparatus, which greatly enhances its hearing capability. The posterior chamber extends along the whole length of the body and is used in buoyancy. Electrophorus has a well-developed sense of hearing. This fish has a vascularized respiratory organ in its oral cavity. As obligate air-breathers, it rises to the surface every 10 minutes or so, and will gulp air before returning to the bottom. Nearly 80% of the oxygen used by the fish is taken in this way. from South America are is largest knifefish Hypopygus lepturus It is part of the family Hypopomidae and is occasionally kept as an aquarium fish. It lives in freshwater and grows up to 10 centimeters long.
- Mooneyes (Hiodontiformes)
- Only two extant species are known to exist in this relatively new order. The larger of the two is the Goldeye (Hiodon alosoides) from the northern rivers of North America, which can reach up to 0.5Â m (1.7Â ft) in length and can weigh 1.8Â kg (4.0Â lb).
- Ribbonfish and allies (Lampriformes)
- The largest member of this small but fascinating order is the aforementioned king of herrings or oarfish (Regalecus glesne), the longest extant bony fish on earth. Another interesting big fish in this order is the Opah (Lampris guttatus), which as opposed to the king of herrings, is massive and has a chunky, rounded shape. Opahs can range up to 2Â m (6.6Â ft) in length and weigh up to 270Â kg (600Â lb).
- Gars (Lepisosteiformes)
- The largest of the gar, and the largest entirely freshwater fish in North America, is the alligator gar (Atractosteus spatula). The largest gar ever known, caught in Louisiana in 1925, was 3Â m (10Â ft) in length and weighed 137Â kg (300Â lb).
- Anglerfish (Lophiiformes)
- The largest of this diverse order is the common goosefish (Lophius piscatorius) of the Northeastern Atlantic off of Europe and North Africa. This big-mouthed fish can attain a size of 58Â kg (127Â lb) and a length of 2Â m (6.6Â ft).
- Lanternfish (Myctophiformes)
- The largest of the numerous but small lanternfish is Bolin's lanternfish (Gymnoscopelus bolini) of the Indo-Pacific oceans, at up to 249Â g (8.8Â oz) and 35Â cm (14Â in).
- Mullets (Mugiliformes)
- The largest of mullets Flathead mullet (Mugil cephalus) have dark centers which give the appearance of a series (6-7) of dark horizontal stripes. The fish grow to lengths up to 60.0Â cm (24Â inches) with weights as high as 4.0Â kg (8.5 pounds).
- Pearlfish and allies (Ophidiiformes)
- The largest member of this order is the widely distributed giant cusk-eels (Lamprogrammus shcherbachevi). A cuskeel can be nearly 2Â m (6.7Â ft) long, but even large fish probably aren't much over 10Â kg (22Â lb) since they are quite slender.
- Smelts and allies (Osmeriformes)
- The largest smelts Rainbow smelt (Osmerus mordax) The body of the rainbow smelt is slender and cylindrical. It has a silvery, pale green back and is iridescent purple, blue, and pink on the sides, with a light underside. When full grown, the rainbow smelt is between 7 and 9 inches (18 and 23Â cm) long and weighs about 3 ounces (85Â g). Individuals over 12 inches (30Â cm) long are known.
- Bony-tongued fish (Osteoglossiformes)
- The largest species is the South American fish usually known as the arapaima (Arapaima gigas). The maximum size this species can attain is a matter of some controversy and some rank it among the world's largest freshwater fishes. No individual arapaima over 3Â m (10Â ft) has been verified and measured. The skeleton of a fish reported to have been measured by native hunters as 4.5Â m (15Â ft) and weighing 200Â kg (440Â lb) when caught, was later examined as a skeleton scientifically and was found to have been roughly within that outsized dimension.
- Perches and allies (Perciformes)
- The title of the largest member of this order, the most numerous order of all vertebrates, is a matter of some debate. A large marlin is the biggest of these fishes: the black marlin (Makaira indica) of the Indo-Pacific, the Atlantic blue marlin (Makaira nigricans) and the Indo-Pacific blue marlin (Makaira mazara). All of these similarly sized species can exceptionally reach up to 5Â m (16Â ft) in length and weight may be as much as 907Â kg (2,000Â lb) or even 1,106Â kg (2,440Â lb). Another notable giant of the perch order is the Atlantic bluefin tuna (Thunnus thynnus) of the Northern Atlantic ocean, which has been verified at up to 4.4Â m (14Â ft) and 679Â kg (1,500Â lb), although can reportedly reach 910Â kg (2,000Â lb). The Swordfish (Xiphias gladius) can reach a maximum weight of 650Â kg (1,400Â lb) and length of 4.5Â m (15Â ft). Due to heavy fishing of both species, swordfish and tuna of great sizes are increasingly rare. One of the largest freshwater fishes is the Nile Perch (Lates niloticus), which grows up to 200Â kg (440Â lb) and 2Â m (6.6Â ft). The biggest of snappers is the Cubera snapper (Lutjanus cyanopterus) of the Caribbean sea and east coast of South America, at a maximum size of 57Â kg (130Â lb) and 1.6Â m (5.2Â ft) in length. The largest species of grunt is the White margate (Haemulon album) of the Caribbean sea and east coast of South America, at up to 7.14Â kg (15.7Â lb) and 0.8Â m (2.6Â ft) in length. The blennies can range up to 0.55Â m (1.8Â ft) in the hairtail blenny (Xiphasia setifer) of the Indo-Pacific. The jacks or mackerels reach their maximum size in the narrow-barred Spanish mackerel (Scomberomorus commerson), which can attain 70Â kg (150Â lb) and 2.4Â m (7.9Â ft). The largest butterflyfish are either the lined butterflyfish (Chaetodon lineolatus) or the saddle butterflyfish (C. ephippium), both of the Indo-Pacific and both of which can measure up to 30Â cm (12Â in). The Freckled darter (Percina lenticula) of the United States, the biggest of the darters, reaching 20Â cm (7.9Â in) and 70Â g (2.5Â oz). The largest drum is the Totoaba (Totoaba macdonaldi) of the Gulf of California, at up to 100Â kg (220Â lb) and 2Â m (6.6Â ft) long. Among the sea bass or groupers, many of which can grow quite large, the greatest size are reached in the Atlantic goliath grouper (Epinephelus itajara). It can reaches a maximum known length of 2.5Â m (8.2Â ft) and weight of 455Â kg (1,000Â lb). The species-rich cichlids reaches their maximum size in the East African Giant Cichlid (Boulengerochromis microlepis), at up to 0.8Â m (2.6Â ft) long and 5Â kg (11Â lb). The humphead wrasse (Cheilinus undulatus) of the Indo-Pacific's coral reefs is by far the largest wrasse, and it can reach a maximum size of 191Â kg (420Â lb) and 2.3Â m (7.5Â ft). Among a fairly small-bodied family, the damselfishes, the Garibaldi (Hypsypops rubicundus) of the Pacific coast of America is the biggest, reaching up to 35.5Â cm (14.0Â in) and 1.2Â kg (2.6Â lb). The Marbled sleeper (Oxyeleotris marmorata) of East Asia is the largest member of the family or sub-order that almost certain contains the smallest living vertebrate, and can reach 0.66Â m (2.2Â ft) long and weigh 9.9Â kg (22Â lb).
- Trout-perch and allies (Percopsiformes)
- The largest species in this small order (both by number of species and body size) is the Sand roller (Percopsis transmontana) of North America. This species can range up to 20Â cm (7.9Â in) in length and can weigh over 11Â g (0.4Â oz).
- Flatfish (Pleuronectiformes)
- The largest of the well-known and heavily fished flatfish is the Pacific halibut (Hippoglossus stenolepis). This giant can reach 363Â kg (800Â lb) and 3Â m (10Â ft), although fish even approaching this size would be extraordinary these days. The Atlantic halibut (Hippoglossus hippoglossus) is also sometimes titled the largest flatfish, although it has a slightly smaller maximum size, at 320Â kg (710Â lb) and 2.8Â m (9.1Â ft).
- Beardfish (Polymixiiformes)
- The little-known beardfish are sometimes classified with the Beryciformes. The largest beardfish is Polymixia busakhini of the Indo-Pacific, which can range up to 0.6Â m (1.9Â ft) in length.
- Bichirs and allies (Polypteriformes)
- The largest bichirs Ornate bichir (Polypterus ornatipinnis) has black and yellow patterning on its body, head, and fins, with 9 to 11 dorsal spines. It is the largest of the Polypterus species with a protruding upper jaw, reaching 24 inches (61Â cm) in length.
- Gulper eels (Saccopharyngiformes)
- The largest gulper eels of eel Pelican eel (Eurypharynx pelecanoides) of the from The pelican eel grows to about 1Â m (3.3Â ft) in length.
- Salmon and allies (Salmoniformes)
- The largest species of salmonid is the taimen (Hucho taimen). The biggest taimen was from the Kotui River in Russia, measuring 2.1Â m (6.9Â ft) and weighing of 105Â kg (230Â lb). Some sources claim the largest is the Chinook salmon (Oncorhynchus tshawytscha) of America's Pacific Northwest, although this species falls behind the taiman in maximum size. The maximum size of this fish is 61.4Â kg (135Â lb) and 1.5Â m (5Â ft) long.
- Sculpins (Scorpaeniformes)
- Although less venomous than many smaller fish in the same order, the skilfish (Erilepis zonifer) of the North Pacific, is largest sculpin. The maximum size is 1.9Â m (6.2Â ft) and the weight can be up to 91Â kg (200Â lb). The Lingcod (Ophiodon elongatus) of the west coast of North America is sometimes listed as the largest sculpin but it is not known to exceed 1.5Â m (5.0Â ft) in length or 60Â kg (130Â lb) in weight. The Cottidae can range up to 0.7Â m (2.4Â ft) and 11Â kg (24Â lb) in the cabezon (Scorpaenicthys marmoratus) of coastal North America.
- Catfish (Siluriformes)
- Most authorities now give the crown of the largest catfish to the Mekong giant catfish, Pangasianodon gigas, which is also considered the heaviest completely freshwater fish. This fish has been recorded at sizes up to 350Â kg (770Â lb) and 3Â m (10Â ft). Closely related to that species, the Asian Giant pangasius (Pangasius sanitwongsei) can grow to 3Â m (10Â ft) and 300Â kg (660Â lb). However, the wels catfish (Silurus glanis) of Europe, at least challenges the proceeding species in massiveness and may surpass them in length. While wels have been confirmed to 3.1Â m (10Â ft), other whiskered giants have been reliably reported to grow to 3.7Â m (12Â ft) and 265Â kg (580Â lb) and more dubiously to 4.3Â m (14Â ft). Another giant of the catfish world is the South American Brachyplatystoma filamentosum, which can reportedly reach 3.6Â m (12Â ft) and 200Â kg (440Â lb).
- Ridgeheads and allies (Stephanoberyciformes)
- Known for flesh that fells flabby to the touch, this order reaches largest sizes in the flabby whalefish (Gyrinomimus grahami) of all southern oceans. This species, which can range up to 0.45Â m (1.5Â ft) in length and weigh 1.5Â kg (3.3Â lb), is sometimes commercially fished.
- Bristlemouths (Stomiiformes)
- The largest of the deep-sea bristlemouths is the short-tailed barbeled dragonfish (Oppostomias micripnus). The top size of a female of this species is probably over 452Â g (1Â lb) and 50Â cm (20Â in) long. In species like the barbeled dragonfish (Idiacanthus atlanticus), the worm-like females can measure up to 0.5Â m (1.7Â ft) long, about 50 times as long as the male. Although Idiacanthus is much more slender and is lighter than Oppostomias.
- Swamp-eels (Synbranchiformes)
- The tropic-dwelling swamp-eels, which are not closely related to true eels, reaches their largest size in the Marbled swamp eel (Synbrachus marmoratus) of Central and South America. This fish can range up to 1.5Â m (4.9Â ft) and weigh 7Â kg (15.4Â lb).
- Seahorses and allies (Syngnathiformes)
- The largest of this diverse order is the red cornetfish (Fistularia petimba), a long, thin species found in all tropical oceans. This fish can reach a length of 2Â m (6.6Â ft) and a weight of 4.65Â kg (10.3Â lb). The largest of the famous, petite seahorses is the Big-belly seahorse (Hippocampus abdominalis) found off of Australia and New Zealand, which can grow to 35Â cm (14Â in) high and weigh over 60Â g (2.1Â oz).
- Pufferfishes and allies (Tetraodontiformes)
- The largest pufferfish is Mbu pufferfish (Tetraodon mbu) its massive size, growing to a length of 67 cm (26 inches). As such, these fish are difficult to adequately house in captivity since they require a very large aquarium and appropriately scaled water filtration. from Congo river are largest triggerfish Titan triggerfish (Balistoides viridescens) to depths of 50Â m (160Â ft) in most of the Indo-Pacific, though it is absent from Hawaii. With a length of up to 75 centimetres (30Â in),
- Dories (Zeiformes)
- The largest species of dory is the Cape dory (Zeus capensis) reaching a size of 90Â cm (36Â in) and a weight of 20Â kg (44Â lb).
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 species measure 9.7Â m (32Â ft) long and weigh an average of 9 tonnes. The largest verified specimen was caught in 1949 off Karachi, Pakistan and was 12.7Â m (42Â ft) long and weighed 21.5Â tonnes. Although many are dubious, there are several reports of larger whale sharks, with reliable sources citing unverified specimens of up to 37Â tonnes and 17Â m (56Â 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 5.5Â m (18Â ft) but even larger ones have been reported. One specimen, a gravid female caught off Australia and measuring only 5.5Â m (18Â ft) long, weighed an exceptional 1,524Â kg (3,360Â lb). A female caught in 1957 reportedly measured 7.4Â m (24Â ft) and weighing 3,110Â kg (6,900Â lb), although this very outsized shark is not known to have been confirmed. The largest of the infamous "requiem sharks" (in the Carcharhinus genus) seems to be the dusky shark (C. obscurus), at up to 4.2Â m (14Â ft) and a weight of 350Â kg (770Â lb). However, the bulkier bull shark (C. leucas) has been estimated to weigh about 575Â kg (1,270Â lb) in recent specimens that measured over 4Â m (13Â ft) long. The largest hammerhead shark is the great hammerhead (Sphyrna mokarran), which can reach 6.1Â m (20Â ft) and weigh 500Â kg (1,100Â lb). The most species-rich shark family, the catsharks, are fairly small-bodied. The largest, the nursehound (Scyliorhinus stellaris), can grow up to 1.7Â m (5.6Â ft) and a weight of at least 10.8Â kg (23.7Â lb).
- 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 1.5Â m (4.9Â ft) in length and weigh 15.4Â kg (34Â lb).
- Frill sharks and cow sharks (Hexanchiformes)
- The largest frill sharks and cow shark is the Bluntnose sixgill shark (Hexanchus griseus). This large species typically inhabits depths greater than 90Â m (300Â ft), and has been recorded as deep as 1,875Â m (6,150Â ft). The largest specimen known (caught off of Cuba) reportedly weighed 763Â kg (1,680Â lb) and measured 4.82Â m (15.8Â ft) long.
- Bull-headed 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 1.65Â m (5.4Â ft) long and weighing up to 20Â kg (44Â lb).
- Mackerel sharks (Lamniformes)
- Most species in this order grow quite large. The largest living species is the basking shark (Cetorhinus maximus) of the world's Northern temperate oceans, also the second largest fish. The largest specimen, which was examined in 1851, measured 12.3Â m (40Â ft) long and weighed 16 tonnes. Perhaps the most famous "big fish", is the great white shark (Carcharodon carcharias). Specimens have been measured up to 6.4Â m (21Â ft) and weighing 3,312Â kg (7,300Â lb), with great whites of at least 7Â m (23Â ft) long generally accepted. The common thresher (Alopias vulpinus), can grow to 7.6Â m (25Â ft) and weigh over 510Â kg (1,100Â lb), but much of its length is comprised by its extreme tail. Odd and recently discovered giants also live in this order: the slender, sword-snouted goblin shark (Mitsukurina owstoni), with unweighed specimens of up to approximately 6.17Â m (20.2Â ft), and the massive megamouth shark (Megachasma pelagios), up to 5.6Â m (18Â ft) long and a weight of 1,215Â kg (2,680Â lb).
- The largest shark in the fossil record is the Megalodon (Carcharodon megalodon or Carcharocles megalodon), a Cenozoic Era relative of the great white shark. The range of estimates of the maximum length for this giant shark are from 17 to 20.3Â m (56 to 67Â ft), with a mass ranging from 65 to 114 short tons (59 to 103Â t). C. megalodon is also regarded as the largest macro-predatory fish ever.
- Stingrays and allies (Myliobatiformes)
- Both the largest species of this order and the largest of all rays is the manta ray (Manta birostris). This peaceful leviathan can reach a size of 3,000Â kg (6,600Â lb), a "disk" width of 9.1Â m (30Â ft) and a total length of 5Â m (16Â ft). A related species reaches barely smaller sizes, the Devil fish (Mobula mobular). It can grow up to a 5.2Â m (17Â ft) disk width, a total length of 6.5Â m (21Â ft) and a weight of at least 1,000Â kg (2,200Â lb). The largest stingray is the generally accepted to be the Short-tail stingray (Dasyatis brevicaudata), found off the southern tip of Africa and Australasia, at up to 4.3Â m (14Â ft) across the disk and weighing more than 350Â kg (770Â lb). Although there are several large stingrays that at least approach this species' size. One, the Giant freshwater stingray (Himantura polylepis), of the large rivers of South Asia, can weigh up to 600Â kg (1,300Â lb), measure up to 5Â m (16Â ft) in total length and have a disc span of 2.4Â m (7.9Â ft).
- Carpet sharks (Orectolobiformes)
- The whale shark is the largest species in this order. No other species in the order even approaches this size. The next largest species is the Nurse shark (Ginglymostoma cirratum), which can grow up to 4.3Â m (14Â ft) across the disk and weighing more than 350Â kg (770Â lb).
- Sawfish (Pristiformes)
- Distinguished by a long snout decorated with sharp teeth on the sides, these little-known cartilaginous fishes are often reported to attain huge sizes. The definitive largest species is not known, although the smalltooth sawfish (Pristis pectinata) and the green sawfish (P. zijsron), at up to reportedly 7.6Â m (25Â ft) and 7.3Â m (24Â ft), respectively, may be the largest. Weights of up to 1,955Â kg (4,310Â lb) have been reported, possibly for the smalltooth species, but are not verified. The large-tooth sawfish (P. perotteti) and freshwater sawfish (P. microdon) can both exceed 6.5Â m (21Â ft).
- Sawsharks (Pristiophoriformes)
- Despite sharing a similar appearing snout adapted in both to shred fish prey, the sawsharks are typically much smaller than sawfish. The largest sawshark is the Sixgill sawshark (Pliotrema warreni) of the South Indian ocean, which can grow up to 1.7Â m (5.6Â ft) and weigh 15Â kg (33Â lb).
- Skates and allies (Rajiformes)
- The largest and most diverse order of rays' largest species is the giant guitarfish (Rhynchobatus djiddensis) of the Red Sea and the eastern Indian ocean. The top size of the species is 227Â kg (500Â lb) and 3.1Â m (10Â ft). The largest of the skates is the common skate (Dipturus batis). This species can grow up to 2.85Â m (9.4Â ft) in length and weigh 97.1Â kg (214Â lb).
- Dogfish and allies (Squaliformes)
- The largest known member of this order is the Greenland shark (Somniosus microcephalus), a giant predator of sub-Arctic waters. This species has been confirmed to as much as 6.4Â m (21Â ft) in length and a weight of 1,397Â kg (3,080Â lb), although specimens of up to 7.3Â m (24Â ft) have been reportedly caught. The Pacific sleeper shark (Somniosus pacificus) has been measured only to 4.4Â m (14Â ft) and 888Â kg (1,960Â lb) in a gravid female, although specimens up to an estimated 7Â m (23Â ft) have been scientifically observed. The Spiny dogfish (Squalus acanthias), a very common species, reaches the largest sizes of the "true dogfish" family. Specimens have been measured at up to 1.6Â m (5.2Â ft) and 9.1Â kg (20Â lb).
- Angelsharks (Squatiniformes)
- The largest of the bottom-dwelling angelsharks (named for their shape rather than disposition) is the Common Angelshark (Squatina squatina) of the northeast Atlantic ocean. This species can grow up to 2.4Â m (8.0Â ft) long and weigh more than 90Â kg (200Â lb).
- Electric rays (Torpediniformes)
- The largest of the electric rays is Atlantic torpedo (Torpedo nobiliana). This fish can measure 1.8Â m (6Â ft) long and weigh 90Â kg (200Â lb). However, a length of 0.6â"1.5Â m (2.0â"4.9Â ft) and weight of 30Â lb (14Â kg) is more typical. Females attain a larger size than males.
Spiny sharks (Acanthodii)
The largest spiny shark was Ischnacanthus. Some species were of large size, up to 2 m in length.
Armored fishes (Placodermi)
The largest known fishes of the now-extinct class Placodermi was Dunkleosteus and Titanichthys. These particular animals may have reached lengths of 10Â m (33Â ft) and are estimated to have weighed in at 3.6 tons.
The hagfish, which are not taxonomically true fish, 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 immediately be distinguished by their strange downward-facing mouth, among other unique morphological features. The largest form is the Goliath hagfish (Eptatretus goliath). This species can range up to 1.28Â m (4.2Â ft) in length and weigh to 6.2Â kg (14Â lb).
As with the similarly unique hagfish, lampreys appear eel-like in shape but are unique enough to earn their own class. These creatures have cartlaginous 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 1.2Â m (3.9Â ft) and weigh 2.5Â kg (5.5Â lb).