What Is the Biggest Fish in the World?

Diver photographing a whale shark
Jones/Shimlock-Secret Sea Visions / Getty Images

The largest fish in the world might surprise you: It is the whale shark. At a maximum length of about 70 feet and weighing up to 47,000 pounds, a whale shark's size rivals that of large whales.

Key Takeaways: The Largest Fish

  • The whale shark is the largest living species of fish. It can grow up to 70 feet long but generally tops out at 40 feet in length.
  • Sharks dominate the list of largest fish with the basking shark (the No. 2 largest fish), great white shark (No. 3), and tiger shark (No. 4). Rounding out the top five is the giant oceanic manta ray (No. 5).
  • Bony fish are also quite large. The largest species of bony fish is the ocean sunfish, which grows as large as 10 feet across its body and 14 feet across its fins, and weighs over 5,000 pounds.

Largest Nonmammalian Vertebrate

The whale shark even sets the record as the largest living nonmammalian vertebrate on land or in the air or water. There are unconfirmed claims of individual whale sharks that are even larger and heavier—70 feet and weighing up to 75,000 pounds.

By comparison, school buses are generally no longer than 40 feet and generally weigh much less. Whale sharks live in tropical oceans and have very large mouths to filter the tiny plankton that is their only food. Their mouths can open up almost 5 feet wide, with over 300 rows housing about 27,000 teeth.

Whale Shark Facts

The whale shark is actually a shark (which is a cartilaginous fish). But these mammals are in no-way viscous man-eaters. According to The American Museum of Natural History: "Despite their (second) name—shark—these giants are so gentle that snorkelers and scuba divers seek them out to swim alongside them." The museum also notes that the whale shark is listed as “vulnerable” on the International Union for Conservation of Nature Red List of Threatened Species due to threats from commercial fishing.

Whale sharks have a beautiful coloration pattern on their back and sides. This is formed by light spots and stripes over a dark gray, blue or brown background. Scientists use these spots to identify individual sharks, which helps them learn more about the species as a whole. Indeed, every whale shark has a unique spot pattern, similar to a human fingerprint. The underside of a whale shark is light.

Distribution and Feeding

The whale shark is found in the pelagic zone in the Atlantic, Pacific, and Indian Oceans. Whale sharks are migratory animals that appear to move to feeding areas in conjunction with fish and coral spawning activity. 

Like basking sharks, whale sharks filter small organisms out of the water. Their prey includes plankton, crustaceans, tiny fish, and sometimes larger fish and squid. Basking sharks move water through their mouths by slowly swimming forward. The whale shark feeds by opening its mouth and sucking in water, which then passes through the gills. Organisms get trapped in small, tooth-like structures called dermal denticles, and in the pharynx. A whale shark can filter over 1,500 gallons of water an hour.

Whale sharks are also amazing swimmers, often moving over 10,000 km each year, and they can dive to around 2,000 meters in depth.

No. 2: The Basking Shark

Basking shark (Cetorhinus maximus), underwater view, Baltimore, Cork, Ireland
Basking Shark. George Karbus Photography/Getty Images 

The second-largest fish is the basking shark, which grows to about 26 feet, but the largest ever accurately measured was 40.3 feet long and weighed over 20,000 pounds. It was caught in 1851 before fishing reduced the population and lifespan so that basking sharks this large are no longer seen. It also is a plankton filter feeder with a very large mouth. It is a commercially harvested fish for food, shark fin, animal feed, and shark liver oil. The basking shark lives in temperate rather than tropical waters, and it is often seen close to land.

Other Large Fish

There is some debate about the order of the next largest fish species in the world. Scientists generally agree that the third- and fourth-largest fish currently living are also sharks and the fifth is a ray species.

Great White Shark

The great white shark, also called the Carcharodon carcharias, can grow up to 13 feet in length, but some great whites have been found to grow up to 20 feet long and weigh more than 2 tons, according to the World Atlas. They can live to be more than 70 years old in waters that are between 54 and 74 degrees Fahrenheit, largely off the coast of California, as well as South Africa, Japan, Oceania, Chile, and the Mediterranean Sea. Most shark attacks that have been recorded on humans are by great white sharks.

Tiger Shark

Also called Galeocerdo cuvier, the tiger shark, or sea tiger, generally grows to 16 feet long and weighs up to 3 tons, but it can grow up to 23 feet in length. The widely distributed species lives mainly in the oceans of the tropics. The distinctive stripes give this species its name.

Giant Oceanic Manta Ray

The Manta birostris, or giant oceanic manta ray, also grows to about 16 feet in length, just a few inches shorter than the tiger shark, but it can grow up to 24 feet. Usually, though, this species of ray tops out at 16 feet, which is why it is classified as the fifth-largest fish, behind the tiger shark. This ray feeds mainly on plankton, alone or in groups

Bony Fish

The other type of large fish is a bony fish. The largest is the ocean sunfish, growing as large as 10 feet across its body,14 feet across its fins, and weighing over 5,000 pounds. These fish eat mostly jellyfish and have a beak-like mouth.

Their size is rivaled by the largest freshwater bony fish, the beluga sturgeon, which is a prized source of caviar. While beluga were once recorded as being as long as 24 feet, with increased fishing they now generally grow to no more than 11 feet long.