Largest Fish in the World: Whale Shark, Basking Shark and More

How the biggest fish are measured

Fish records are slippery. Very large fish are rarely weighed whole, many old records come from harpooned or stranded animals measured without witnesses, and sizes reported by fishermen or sailors tend to grow with each retelling. Scientists usually give total length, from snout to the tip of the tail, and treat any figure without a measured specimen as an estimate.

It also matters which “fish” you mean. Sharks and rays have skeletons of cartilage, while bony fish such as sunfish, sturgeon and tuna have skeletons of bone. Whales and dolphins are not fish at all: they are mammals, which is why the blue whale, the largest animal ever known, does not appear on this list. See our comparison of the whale shark vs blue whale for how the two giants differ.

1. Whale shark: the biggest fish alive

The whale shark (Rhincodon typus) lives in tropical and warm-temperate seas around the world. Growth studies suggest that males mature at about 8–9 m (26–30 ft) and that females grow larger. The most reliable record is a female from the Arabian Sea, reported in 2001, with a measured standard length of 15 m (49 ft) and an estimated total length of 18.8 m (62 ft). Older reports of 20 m (66 ft) or more lack solid documentation.

Few whale sharks have ever been weighed. A shark of about 12 m (39 ft) is estimated to weigh roughly 15–20 tonnes (16–22 short tons). Despite their size, whale sharks are filter feeders that sieve plankton, fish eggs and small schooling fish from the water, and they are harmless to people. The IUCN lists the species as Endangered after steep declines caused by fishing, bycatch and ship strikes.

2. Basking shark: the second-largest fish

The basking shark (Cetorhinus maximus) is the largest fish in cooler waters. It regularly reaches 7–8.5 m (23–28 ft), and an average adult of about 7.9 m (26 ft) weighs around 4.6 tonnes (5 short tons). The largest recorded specimen, trapped in a herring net in the Bay of Fundy, Canada, in 1851, measured 12.27 m (40.3 ft) and was estimated at 16 tonnes, but modern growth studies suggest that animals over about 10 m (33 ft) are very rare.

Like the whale shark, it is a filter feeder. It swims slowly at the surface with its huge mouth open, straining tiny zooplankton through its gill rakers. Basking sharks are regularly seen in summer off Cornwall, the Isle of Man, western Scotland and Ireland, and along both coasts of North America. The species is listed as Endangered.

3. Great white shark: the largest predatory fish

The great white shark (Carcharodon carcharias) is the biggest fish that hunts large prey. Females mature at about 4.6–4.9 m (15–16 ft) and typically weigh 1,000–1,900 kg (2,200–4,200 lb); males are smaller. A 2014 review of catch records found the longest reliably measured white shark to be 6.02 m (19.8 ft) and the heaviest 2,530 kg (5,580 lb). Claims of 8–11 m (26–36 ft) giants have been discredited.

Two other sharks rival it for bulk. The Greenland shark of the cold North Atlantic usually reaches 4–5 m (13–16 ft), with confirmed specimens of up to 6.4 m (21 ft) weighing over 1,000 kg (2,200 lb). The tiger shark has been verified at about 5.5 m (18 ft).

4. Giant oceanic manta ray: the largest ray

The giant manta ray (Mobula birostris) is the largest ray on Earth. A typical adult measures about 4.5 m (15 ft) across its wing-like pectoral fins, and the largest reach about 7 m (23 ft). The heaviest are estimated at up to around 2–3 tonnes. It feeds on zooplankton in tropical and subtropical oceans, and it has one of the largest brains of any fish. It is listed as Endangered because it breeds very slowly and is caught in fisheries.

5. Beluga sturgeon: the giant of the Caspian Sea

The beluga sturgeon (Huso huso) of the Caspian and Black Sea basins is the largest sturgeon and, after the sunfish, the heaviest bony fish on record. It lives in the sea and migrates up large rivers such as the Volga to spawn. The largest accepted record, a female caught in the Volga estuary in 1827, measured about 7.2 m (24 ft) and weighed about 1.5 tonnes (3,300 lb); different sources give 1,474–1,571 kg for that fish.

Today, adults caught are much smaller, usually about 1.4–3.3 m (4.7–10.8 ft) and 19–264 kg (42–582 lb). Overfishing for caviar has pushed the species to Critically Endangered, and big old females have almost disappeared.

6. Sunfish: the heaviest bony fish

Sunfish are tall, flattened fish that look like a head with fins attached. In late 2021, a dead giant sunfish (Mola alexandrini) found off Faial Island in the Azores weighed 2,744 kg (6,049 lb) and measured 3.25 m (10.7 ft) long. It is the heaviest bony fish ever recorded, beating a 2,300 kg (5,100 lb) specimen caught off Japan in 1996.

The more familiar ocean sunfish (Mola mola) is almost as large. Adults average about 1.8 m (5.9 ft) in length and usually weigh 247–1,000 kg (545–2,205 lb), and much larger individuals are occasionally found. Sunfish feed largely on jellyfish and other soft-bodied prey, and the ocean sunfish is listed as Vulnerable, mainly because so many are caught as bycatch.

7. Giant oarfish: the longest bony fish

The giant oarfish (Regalecus glesne) is a ribbon-shaped, silvery fish with a red crest, found in deep water in oceans around the world. It is commonly about 3 m (10 ft) long, and the longest reliable records are about 7–8 m (23–26 ft), possibly up to 11 m (36 ft); the heaviest weighed about 272 kg (600 lb). Older claims of 15 m (50 ft) or more are considered very likely to be wrong.

Because oarfish are rarely seen alive and sometimes wash ashore, they may lie behind some sea serpent stories. In Japan, they are said to appear before earthquakes, but a 2019 study comparing sightings with earthquake records found no link.

Other giants of the sea

Several other bony fish can exceed 600 kg (1,300 lb). Atlantic bluefin tuna have been verified at up to about 680 kg (1,500 lb). Blue and black marlins can reach about 4–5 m (13–16 ft), and the largest reliably weighed have exceeded 700 kg (1,500 lb). Among sharks, the great hammerhead can reach about 6 m (20 ft), and the megamouth shark, first discovered only in 1976, about 5.5 m (18 ft).

Largest freshwater fish

Measuring freshwater giants is tricky, because sturgeon and some other big fish move between rivers and the sea. Counting only fish that spend their whole lives in fresh water:

• Giant freshwater stingray (Urogymnus polylepis): in June 2022, a female caught in the Mekong River in Cambodia weighed 300 kg (661 lb) and measured about 4 m (13 ft) long, the heaviest strictly freshwater fish ever documented. She was tagged and released.
• Mekong giant catfish (Pangasianodon gigas): a female caught in northern Thailand in 2005 weighed 293 kg (646 lb) and measured 2.7 m (8.9 ft). The species is Critically Endangered.
• Arapaima (Arapaima gigas): the air-breathing giant of the Amazon reaches more than 2 m (6.6 ft), with verified records of about 3 m (10 ft) and 200 kg (440 lb).
• Wels catfish (Silurus glanis): Europe’s largest freshwater fish has been recorded at more than 2.5 m (8 ft) and over 100 kg (220 lb).
• Alligator gar (Atractosteus spatula): the largest fish living only in North American fresh water. One caught in Mississippi in 2011 weighed 148.5 kg (327 lb).

In North America, the white sturgeon of the Pacific Northwest grows even larger, with a maximum recorded length of 6.1 m (20 ft), but some populations spend part of their lives at sea.

Megalodon: the largest fish that ever lived

The biggest fish known to science is extinct. Megalodon (Otodus megalodon) was a giant shark that lived from roughly 23 to 3.6 million years ago. It is known almost entirely from teeth, which can be up to about 18 cm (7 in) long, and a few vertebrae, so its size must be estimated. Published estimates range from about 14 to 24 m (47–80 ft), with many studies placing the largest individuals at roughly 15–20 m (50–65 ft). Despite many rumors, megalodon is not alive today.

Largest fish compared