Here are the top six largest fish species (within around 33,100 described species).

But, first of all, what is a fish? At first, it looks like an easy question, but in fact, it is not. There is a wide range of animals we call “fish”, so it is not easy to define what makes a fish “a fish”. A general description: “a fish is any member of a paraphyletic group of organisms that consist of all gill-bearing aquatic craniate animals that lack limbs with digits” (Wikipedia).

All fishes have a brain protected by a braincase, and an obvious head region with eyes, teeth, and other sensory organs.

Most fishes:

are vertebrates with vertebrae protecting the spinal cord.

live in water.

breathe primarily with gills rather than lungs.

have paired limbs, in the form of fins that aid in locomotion.

are unable to regulate their own internal body temperatures.

are covered with scales that protect their bodies.

But there are exceptions: hagfish aren’t vertebrates and don’t have scales; mudskippers can live outside the water, lungfish use lungs to breathe, lampreys don’t have paired fins, and tuna are warm-blooded.

Fish can be found in nearly all aquatic environments, from high mountain streams (e.g., char and gudgeon) to the abyssal and even hadal depths of the deepest oceans (e.g., gulpers and anglerfish); in environments as hot as 104°F/40°C and as cold as 28°F/-2°C.

And here are our top six largest living fish, in reversed order.

List of largest fish species

6. Great White Shark (up to 6.4 meters / 21 feet)

Largest fish species: The great white shark (Carcharodon carcharias), also known as the great white, white pointer, white shark, or white death, is a species of large lamniform shark which can be found in the coastal surface waters of all the major oceans. The great white shark is mainly known for its size, with mature individuals growing up to 6.4 m (21 ft) in length.

The great white shark (scientific name: Carcharodon carcharias) is the largest predatory fish on Earth. According to the Guinness World Records Book, full-grown adults are average 4.3-4.6 m (14–15 ft) in length and generally weigh 520-770 kg (1,150-1,700 lb). But they can grow up to 6.4 meters / 21 feet, and there are many claims of huge specimens up to 10 m (33 ft) in length (most of these claims are unverifiable, and probably false).

The star of the summer blockbuster, the great white shark is the world’s largest flesh-eating fish. These seals don’t have a prayer against its weapon of choice: up to 300 serrated teeth.

5.Beluga (sturgeon) (up to 7.2 meters / 23 feet 8 in)

Largest fish species: A beluga or European sturgeon (Huso huso) captured in 1922 in the Volga Estuary. It is not a record-breaker, but probably at 7 meters (23 feet), one of the largest European sturgeons ever caught.

The beluga or European sturgeon (Huso huso) is a large predator which feeds mostly on fish, also rarely consuming waterfowl and seal pups. It is a species of anadromous fish (the fish migrate from the sea up into freshwater to spawn; examples are salmon and striped bass – Greek: ἀνά ana, “up” and δρόμος dromos, “course”) in the sturgeon family (Acipenseridae) of order Acipenseriformes. It is found primarily in the Caspian and Black Sea basins, and occasionally in the Adriatic Sea.

The largest accepted record is of a female taken in 1827 in the Volga estuary at 1,571 kg (3,463 lb) and 7.2 m (23 feet 8 in). Several other records of aged sturgeon exceed 5 m (16 ft). These great sizes mark the beluga as the largest freshwater fish in the world.

4. Greenland Shark (up to 7.3 meters / 24 feet)

Largest fish species: Greenland Shark

Greenland Shark lives farther north than any other shark species. It is one of the largest living species of shark, of dimensions comparable to those of the great white shark. Greenland sharks grow to 6.4 m (21 ft) and 1,000 kg (2,200 lb), and possibly up to 7.3 meters (24 ft) and more than 1,400 kg (3,100 lb). However, most Greenland sharks observed have been around 2.44-4.8 meters (8.0-15.7 ft) long and weigh up to 400 kg (880 lb).

The Greenland shark has a sluggish look, with a thickset, cylindrical body and a small head with a short snout and tiny eyes. Their maximum speed is a lethargic 1.7 miles per hour, many are almost blind, and they are happy to eat rotting carcasses: they particularly prefer the tastes of Narwhal and Beluga whale carcasses, and they sometimes participate in cannibalism. Furthermore, these sharks also enjoy seals, cetaceans, sea lions, salmon, lumpfish, halibut, char, capelin, herring, and other fish.

3. Basking Shark (up to 8 meters / 26 feet)

Largest fish species: Basking shark (Cetorhinus maximus). Photo: Wikipedia

The basking shark (Cetorhinus maximus) is the second-largest living fish on Earth and one of three plankton-eating sharks besides the whale shark and megamouth shark. It can be found in all the world’s temperate oceans. It is a slow-moving filter feeder and has anatomical adaptations for filter feeding, such as a greatly enlarged mouth and highly developed gill rakers. Adults typically reach 6-8 meters (20-26 feet) in length.

2. Giant Oarfish (up to 11 meters / 36 feet)

Giant Oarfish is the longest bony fish on Earth. Although they commonly measured up to 3 meters (9.8 feet) in total length, they can grow a record length of 11 meters (36 feet). They are rarely seen because the Giant Oarfish live at depths around 3,300 feet (1,000 meters).

Largest fish species: Members of a BUD/S class display a 23-foot (7 m) giant oarfish discovered by their instructor on the beach of Naval Amphibious Base Coronado in 1996. Photo: Wikipedia



1. Whale Shark (12.65 meters /41.50 feet) – the largest fish in the world

Largest fish species: The whale shark (Rhincodon typus) is a slow-moving filter feeding shark and the largest known extant fish species. Here is a whale shark swimming within divers at the Ahe dive resort, Harlem Islands, Papua. Photo: scubasigns.org

The whale shark (Rhincodon typus) is the largest known extant fish species. It is a slow-moving filter feeding shark. The largest confirmed individual had a length of 12.65 m (41.50 ft) and a weight of about 21.5 metric tons (47,000 lb), and unconfirmed reports of considerably larger whale sharks exist. Claims of individuals over 14 m (46 ft) long and weighing at least 30 metric tons (66,000 lb) are not uncommon.

Whale sharks have a mouth that can be 1.5 m (4.9 ft) wide, containing 300 to 350 rows of tiny teeth and 10 filter pads which it uses to filter feed.

Size of the Whale shark compared to an average human. The largest confirmed individual had a length of 12.65 m (41.50 ft) and a weight of about 21.5 metric tons (47,000 lb). Photo: Wikipedia

Largest fish species: In this exciting episode of Shark Academy, Jonathan dives into the world of the world’s largest shark, and in general, the largest fish–the Whale shark! Is it a whale or a fish? You will be an expert in 4 minutes!

The video below captured and submitted by GoPro Awards recipients shark biologist and freediver Ocean Ramsey and Juan Oliphant. They swim with whale sharks in the Philippines to document migrating populations. Whale shark populations are at an all-time low due to finning, fishing bycatch, entanglement, speedboat prop collisions, and death by ingestion of floating debris.

The largest fish in the oceans: captured and submitted by GoPro Awards recipients Ocean Ramsey and Juan Oliphant.

Join shark biologist and freediver Ocean Ramsey as she films with whale sharks in the Philippines to document migrating populations. Whale shark populations are at an all-time low due to finning, fishing bycatch , entanglement, speedboat prop collisions, and death by ingestion of floating debris.

Some other big fish species

There are some other living big fish species that can be included in this list. For example, the common thresher (Alopias vulpinus), can grow to 7.6 m (25 ft) and weigh over 510 kg (1,120 lb), but much of its length is comprised by its extreme tail, so I didn’t include it in the original list.

Largest fish species: Common thresher. Photo: endangeredspecieslawandpolicy.com

Another example, the Sawfish (Pristiformes): 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 7.6 and 7.3 meters (25 and 24 feet), respectively, may be the largest. Weights of up to 1,955 kg (4,310 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 6.5 meters (21 feet). Much of their length is comprised by their long “saw” noses.

Largest fish species: The smalltooth sawfish (Pristis pectinata), also known as the wide sawfish, is a sawfish of the family Pristidae. It is found in shallow tropical and subtropical waters in coastal parts of the Atlantic, including the Mediterranean. Reports from elsewhere are now believed to be misidentifications of other species of sawfish. This critically endangered species reaches a length of up to 7.6 meters (25 feet). Photo: Wikipedia

The heaviest living bony fish: Ocean sunfish

Largest fish species: The ocean sunfish is the heaviest of all bony fish. It has a flattened body and is as tall as it is long. It feeds mainly on jellyfish. The mature ocean sunfish has an average length of 1.8 meters (5.9 feet) and a fin-to-fin length of 2.5 meters (8.2 feet). The average weight of mature specimens can range from 247 to 1,000 kg (545 to 2,205 lb) Even larger individuals are not unheard of. The maximum size is up to 3.3 meters (10.8 feet) in length 4.2 meters (14 feet) across the fins and up to 2,300 kg (5,100 lb) in mass. Photo: savenaturesavehuman.blogspot.com

The ocean sunfish, or common mola, Mola mola is the heaviest of the bony fish in the world. The mature ocean sunfish has an average length of 1.8 meters (5.9 feet) and a fin-to-fin length of 2.5 meters (8.2 feet). The average weight of mature specimens can range from 247 to 1,000 kg (545 to 2,205 lb) Even larger individuals are not unheard of. The maximum size is up to 3.3 meters (10.8 feet) in length 4.2 meters (14 feet) across the fins and up to 2,300 kg (5,100 lb) in mass.

Update (July 24, 2017): Researchers Just Discovered A New Species Of the Ocean Sunfish

On July 20, 2017, National Geographic has announced that researchers have discovered a new species of the Ocean Sunfish. It has been named the Hoodwinker sunfish (Mola tecta) and is the first species of Ocean Sunfish to be identified in 130 years – somehow it has escaped taxonomy records for almost three centuries.

Here is the video published by the National Geographic below:

Prehistoric records – largest fish species ever lived

Megalodon – The largest shark ever lived on earth (up to 18 meters / 59 feet)

Megalodon (meaning “big tooth”, from Ancient Greek) is an extinct species of shark that lived approximately 15.9 to 2.6 million years ago, during the Cenozoic Era (middle Miocene to end of Pliocene). Fossil remains suggest that this giant shark reached a length of 18 meters (59 feet).

Megalodon had the most powerful bite of any creature that has ever lived: it is estimated that the bite force of a Megalodon’s jaws could generate somewhere in the vicinity of 108,514 N – 182,201 N (11-18 tons of force). For reference, this is about 6-10 times the biting power of a Great White Shark and 18-30 times that of a Lion. It is strong enough to crush an automobile and even far exceeded that of the Tyrannosaurus rex, which was capable of a maximum bite force of 35,000 to 57,000 newtons at its back teeth.

Largest fish species (historic): Megalodon (gray and red) with the whale shark (violet), great white shark (green), and a human (black) for scale. Note: The maximum size attained by megalodon is indicated by the 20 m scale. Photo: Wikipedia

Reconstruction of the megalodon jaws by the American zoologist Bashford Dean (October 28, 1867 – December 6, 1928) in 1909, with fossil teeth assembled from various localities. Photo: Wikipedia

Life restoration of the megalodon, the largest shark ever lived. Photo: Wikipedia

Largest known fish ever lived: Leedsichthys (22 meters / 72 feet)

The largest-ever known bony fish was Leedsichthys, of the Jurassic period in what is now England. Estimates of the size of this fish range from 21 to 27 meters (69 to 89 feet) and mass from 20 to 50 tons. A maximum size of 22 meters (72 feet) and 25-30 tons has been deemed to be most realistic.

Largest fish ever lived: Leedsichthys Restoration based on the modern interpretation of the fossils. Image: Wikipedia

Sources