Cambodia Giant Freshwater Stingray

Fish experts believe the giant stingray, such as this one in Cambodia's Mekong River, is the largest freshwater species on Earth. This specimen measured more than 13 feet (4 meters) long.

 The Cambodia giant freshwater stingray is one of the largest and heaviest freshwater fishes in the world. Only described by scientists in 1990, the giant freshwater stingray occurs in several river systems in Southeast Asia and northern Australia. While Australian populations – which generally average much smaller than those in Southeast Asia – appear to be stable, giant freshwater stingrays have been under serious decline in Thailand, where they are now listed as critically endangered. In Cambodia, not much is known about this species’ status in the Mekong River, and more research is needed to develop an effective species management plan. As a benthic feeder foraging on the river bottom, these stingrays are especially vulnerable to increasing siltation due to human activity as well as to isolation of reproductive subpopulations through construction of large-scale hydropower dams.

The giant stingray is also cloaked in mystery. No one is sure how many giant stingrays are left, which habitats they prefer, or even if they ever venture into the ocean, where their more commonly known relatives dwell.
These ancient fish, little changed over many millions of years, can reach 16.5 feet (5 meters) long and weigh up to 1,320 pounds (600 kilograms). They are brown to gray in color, wide and flat in form, and they sport a long, whiplike tail.
Stingray numbers appear to have dropped dramatically in recent years as their riverine habitats have degraded, and it appears they no longer inhabit some parts of their historical range. Large stingrays have been known to pull boats upstream and even underwater.
Though stingrays do not readily attack humans, they are one of the few megafishes that can pose a real danger to those who handle them. Each ray sports a deadly barb on the base of its tail that can easily penetrate human skin and even bone, much like a hunting arrow. This stinger can be as long as 15 inches (38 centimeters) and typically introduces toxins to the victim's wound.

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