What is the World’s Largest Freshwater Fish? All About the Record-Breaking Giant Stingray

Imagine pulling a fish from a river that weighs as much as a large motorcycle and stretches nearly as long as a small car. That is exactly what happened in Cambodia’s Mekong River, where a giant freshwater stingray weighing around 300 kg (661 lb) was documented.

The enormous female stingray measured almost 4 metres (13 feet) from snout to tail, with a disc approximately 2.2 metres (7 feet 2 inches) wide. Its extraordinary dimensions earned it recognition as the world’s largest freshwater fish ever recorded by weight.

Which is the World’s Largest Freshwater Fish?

The giant freshwater stingray (Urogymnus polylepis) holds the record for the largest freshwater fish ever recorded.

The record-breaking specimen weighed approximately 300 kg and was discovered in the Mekong River in Cambodia. Its enormous size surpassed the previous record associated with a giant Mekong catfish.

Unlike marine rays that may occasionally enter rivers, the giant freshwater stingray is adapted to freshwater environments and can spend much of its life along the bottom of large rivers.

Where Was the 300-Kg Giant Stingray Found?

The record-breaking stingray was caught by local fishermen in the Mekong River in the Stung Treng region of northern Cambodia.

The female stingray weighed approximately 300 kg, or 661 pounds. From the front of its body to the end of its tail, it measured nearly 4 metres.

Its disc—the broad, flattened portion of a stingray’s body—measured approximately 2.2 metres across.

To put that into perspective, its overall length was comparable to that of a small car.

How Big Was the Record-Breaking Stingray?

The dimensions of the giant stingray demonstrate just how large freshwater species can become.

Feature	Measurement
Species	Giant freshwater stingray
Scientific name	Urogymnus polylepis
Weight	Around 300 kg (661 lb)
Total length	Nearly 4 metres (13 ft)
Disc width	Around 2.2 metres (7 ft 2 in)
Location	Mekong River, Cambodia
Region	Stung Treng
Habitat	Freshwater rivers

Its broad, flattened body allows the stingray to live close to the riverbed, where it can remain relatively well hidden despite its enormous size.

Why is the Giant Freshwater Stingray So Special?

What makes this animal particularly remarkable is that it is a genuine freshwater giant.

Many of the world’s biggest fish, such as whale sharks and large sharks, live in oceans. The giant freshwater stingray, however, inhabits river systems.

The species spends much of its time close to the bottom, where its flattened body helps it move along sandy or muddy riverbeds.

Because of this behaviour, even extremely large individuals may remain difficult for people to observe.

Giant Stingray Enters the Record Books

The approximately 300-kg specimen attracted international attention because of its record-breaking weight.

It was recognised as the largest freshwater fish ever recorded, drawing global attention not only to the animal itself but also to the extraordinary biodiversity of the Mekong River.

Before this stingray, a 293-kg Mekong giant catfish caught in Thailand in 2005 was widely recognised as the record holder.

The Cambodian stingray surpassed that weight by approximately 7 kg.

Is the Mekong River Hiding More Giant Fish?

The discovery raises an intriguing question: could even larger freshwater animals still be living beneath the Mekong?

The Mekong is one of Asia’s great river systems and supports an enormous variety of aquatic life.

Its waters are known for several exceptionally large freshwater species, including giant stingrays, Mekong giant catfish and giant barbs.

The river’s size and complex underwater habitats also mean that some large animals can remain difficult to study.

Scientists therefore continue to investigate the biodiversity of the Mekong and the conditions that allow giant freshwater species to survive.

Where Does the Mekong River Flow?

The Mekong is one of the longest and most important rivers in Asia.

It originates in the Tibetan Plateau and travels through or along several countries before eventually reaching the South China Sea.

Its basin supports millions of people who depend on the river for food, fishing, agriculture, transportation and livelihoods.

The Mekong is also considered an important global centre of freshwater biodiversity.

Why Are Giant Freshwater Stingrays Important to Scientists?

Studying giant freshwater stingrays can provide scientists with valuable information about the health of large river ecosystems.

Large aquatic animals generally require extensive habitats, adequate food resources and suitable environmental conditions to survive.

Changes in water quality, fishing pressure, dams and modifications to natural river habitats can therefore affect their populations.

Tracking and studying these animals can help researchers better understand how environmental changes are influencing the wider Mekong ecosystem.

What Threatens Giant Fish in the Mekong River?

Despite its extraordinary biodiversity, the Mekong faces several environmental pressures.

Habitat modification, dam construction, overfishing and changes in river conditions can affect migratory routes, breeding grounds and food availability for freshwater species.

Large fish can be particularly vulnerable because many grow slowly, require extensive habitats and may take years to reach maturity.

Protecting these species therefore also means protecting the river ecosystems on which they depend.

Giant Freshwater Stingray vs Mekong Giant Catfish

Before the Cambodian stingray was documented, the Mekong giant catfish was associated with the freshwater fish size record.

Giant Freshwater Stingray	Mekong Giant Catfish
Around 300 kg	Around 293 kg
Found in Cambodia	Record specimen caught in Thailand
Recorded in the Mekong River	Recorded in the Mekong River
Broad, flattened body	Large catfish body
Current record-breaking specimen	Previous record holder

The difference between the two record specimens was only about 7 kg, demonstrating the remarkable size of the Mekong’s freshwater giants.

Key Facts About the World’s Largest Freshwater Fish

• The giant freshwater stingray is scientifically known as Urogymnus polylepis.
• A record-breaking female weighed approximately 300 kg or 661 lb.
• It was documented in Cambodia’s Mekong River.
• The specimen measured nearly 4 metres from snout to tail.
• Its disc was approximately 2.2 metres wide.
• It surpassed the previous 293-kg Mekong giant catfish record.
• Giant freshwater stingrays generally live close to riverbeds.
• The species is one of several exceptionally large fish associated with the Mekong ecosystem.

A Giant Worth Protecting

The 300-kg giant freshwater stingray is more than an extraordinary entry in the record books. Its existence demonstrates how much remarkable wildlife can remain hidden beneath the surface of the world’s great rivers.

For researchers, encounters with giant freshwater stingrays provide opportunities to learn more about the biodiversity and ecological health of the Mekong. Protecting these enormous fish also means conserving the freshwater ecosystems that support countless other species and millions of people.

The record-breaking stingray therefore serves as both a symbol of the Mekong’s extraordinary biodiversity and a reminder of why the world’s great freshwater ecosystems need protection.