English name: Rainbow Water Snake (aka “Rainbow Mud Snake”, “Striped Water Snake”, “Schneider’s Water Snake”)
Scientific name: Enhydris enhydris
Thai name: Ngu Sai-rung, Ngu Plaa
Description: To 97cm long. Robust body with relatively small head for a water snake. Scales are smooth and iridescent. Olive-brown above with two yellow or reddish stripes bordered by dark stripes on the top and sides. White to yellow below with a dark stripe or dots down the center of belly.
Similar Species: Yellow-bellied Water Snake has a broader head and lacks colored lines.
Sunbeam Snake has a wedge-shaped head, more iridescent scales, and lacks colored lines on its body.
Red-tailed Pipe Snake lacks colored lines and has a barred underbelly.
Chanard’s Mud Snake has a broader head and dark spots above the line running down its side.
Jagor’s Water Snake has a broader head and dark blotches running down its side.
Habitat: A highly aquatic species that is always found in or near wetlands. Is found in a wide range of aquatic habitats, including manmade lakes and ponds. Spends most of its time hunting just off the shore, taking advantage of the tangles of vegetation in the mud at the water’s edge. Is rarely seen in the open, preferring to remain underwater or within vegetation mats and tangles. Does not tolerate brackish water.
Contribution to the ecosystem: Primarily keeps fish populations in balance, but also feeds on frogs and tadpoles. Provides food for larger snakes, large fish, monitors, and wading birds.
Danger to humans: Like other water snakes in its family, the Rainbow Water Snake has a very mild rear-fanged venom that does not pose a threat to humans.
Conservation status and threats: Due to its ability to survive in a wide range of habitats and tolerate human encroachment, the Rainbow Water Snake is a very common species in Thailand. However, a recent significant increase in the harvest of water snakes in Cambodia (for food, skins, and crocodile feed) has led to declines in some populations there. As many as four million Rainbow Water Snakes are estimated to be captured from the Tonle Sap Lake every year.
Interesting facts: Water snakes have a number of specialized traits to support their aquatic lifestyle. These include eyes positioned on top of the head (to see prey and threats while remaining underwater), nostrils that can be closed while underwater, and young that are born live (eliminating the need for a dry place to lay eggs).
The IUCN Red List: Enhydris enhydris
Reptile Channel: Mud Snakes
Semi-aquatic Snake Communities in the Central Plain Region of Thailand
The Ecology of the Water Snakes of Ban Tha Hin, Songkhla Province, Thailand
Nature Malaysia: Rainbow Water Snake
Thailand Office of Environmental Planning and Policy: A Checklist of Amphibians and Reptiles in Thailand
A Photographic Guide to Snakes and Other Reptiles of Peninsular Malaysia, Singapore and Thailand
A Field Guide to the Reptiles of South-East Asia
A Field Guide to the Snakes of South Vietnam