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5 of the Biggest Fish in the World

5 of the Biggest Fish in the World

Written by Scuba.com
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Updated on June 14, 2023
Female diver swimming with whale shark

The oceans of the world are home to the most diverse life on the planet. They come in all forms, shapes, colors, and sizes. And while some marine creatures are unimaginably tiny, others are truly massive! The biggest fish in the world reside within the oceans and are truly majestic species.

Many ocean fish could compete for the title of the biggest based on size and weight, but there are a few fascinating fish that are just astoundingly larger than the rest. Let’s learn more about the ocean’s biggest fish below.

5 Biggest Fish in the World

Here are the five biggest fish that rule the ocean. Some of them may not be easily found, but with the right tour guides and some luck, you may be able to get a glimpse of these truly majestic sea creatures!

Whale Shark

Divers swimming with whale shark
Image via Shutterstock

Without question, the biggest fish in the world is the whale shark. The whale shark is not actually a whale but a type of peaceful shark that freely feeds on plankton and small fish with its mouth wide open (called filter feeding) near the surface of warm and warm-temperate seas. These docile fish can weigh up to 47,000 pounds and grow anywhere between 31 to 42 feet long, although some have reported seeing much larger whale sharks.

Because of their size, their dark grey to brownish bodies with white spots are a lot easier to spot all tropical seas. They may even allow you to hitch a ride on their backs!

Basking Shark

Basking shark with mouth open
Image via Shutterstock

The second largest fish in the world is the basking shark, whose body ranges from very dark gray to grayish brown. And like the whale shark, it’s a peaceful type of shark that opens its mouth wide open to filter feed on plankton while swimming. It can grow anywhere between 20 to 40 feet and generally weighs about 11,400 pounds. They can be spotted in coastal waters around the world, moving slowly near the surface of the water where it is much warmer. This explains where it got its name.

Sadly, overfishing has made them a somewhat rare sight.

Oarfish

Oarfish are extremely large, ocean-dwelling lapriform fish with greatly elongated bodies. They are found in temperate and tropical oceans but are rarely seen after they reach their adult size. The giant oarfish is considered the longest bony fish alive while the King of Herrings, another type of oarfish, usually weighs only 600 pounds but can grow to about 50 feet long. They feed on zooplankton, as well as small fish, jellyfish, and squid.

Although oarfish are considered prized fishing baits, they are rarely caught alive and are not actually good for eating due to their gelatinous flesh. They also occasionally linger near the surface of the water when they’re sick or dying, which probably links them to sea serpents in mythological tales.

Mola Mola (Ocean Sunfish)

Mola mola ocean sunfish ocean biggest fish
Image via Shutterstock

Ocean sunfish, also called Mola mola, are some of the largest, strangest looking fish on the planet. These giant fish have a long and laterally flattened body with long dorsal and ventral fins that can make them equally tall and long. They mostly feed on large amounts of sea jellies, usually grow to about 8 feet across and 6 feet long, and generally weigh between 2,000 and 3,000 pounds.But much larger specimens, some weighing over 5,000 pounds, have also been recorded.

Adult ocean sunfish are commonly found in temperate and tropical ocean waters around the world, but they occasionally swim through kelp and deep coral reefs.

Manta Ray

Manta Ray ocean biggest fish
Image via Shutterstock

The manta ray is another of the world’s biggest fish. Manta rays grow up to around 9 to 12 feet long but also have giant “wingspans” that can spread out wide, measuring anywhere between 18 to 23 feet. These “wings” allow them to ”glide” through the water like flying kites. And like other large fish, they feed on plankton and small fish, as well as segmented worms. They are usually found in the tropical and subtropical parts of the world’s oceans.

Manta rays are light for their size, usually only weighing about 3,000 pounds. And like every large fish in this list, they are harmless and like to swim curiously around divers. You may even spot them jumping out of the water when they have to get rid of parasites.

Biggest Fish Comparison Chart

 Whale SharkBasking SharkOarfishOcean SunfishManta Ray
Size31 to 42 feet20 to 40 feetAbout 50 feet longAbout 6 feet long and 8 feet across9 to 12 feet long, 18 to 23 feet across
Weight47,000 lbs.11,400 pounds600 pounds2,000 to 3,000 poundsNearly 3,000 pounds
Distinctive FeaturesBig mouth opening, dark grey to brown body, white spotsBig mouth opening, very dark gray to grayish brown bodyLapriform fish with large, elongated bodiesLong and laterally flattened body, long dorsal and ventral finsFlat body with giant, triangular pectoral “bird” fins
HabitatWarm and warm-temperate seasCoastal watersTropical and temperate oceansTropical and temperate oceansTropical and subtropical parts of oceans
PreyPlankton and small fishPlanktonZooplankton, small fish, jellyfish, squidlarge amounts of sea jelliesPlankton, small fish, segmented worms

Have you seen any of these fish? Share with us your first impressions and experiences below!

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Our team of experts and scuba diving pros at Scuba.com share their knowledge of the underwater world.