English name: Mekong Mud Snake
Scientific name: Enhydris subtaeniata
Thai name: ngu sai rung lai
Description: To 75cm long. A short but thick-bodied snake with head only slightly thicker than the neck. Body is brownish or grayish, often darker on the top than on the sides, with rows of indistinct black markings on both the top and sides. Some specimens have a reddish line between the dark upper markings and dark side markings. Belly is cream-colored, sometimes with a pair of reddish lines on each side.
Similar Species: Jagor’s Water Snake is thicker, has larger black blotches, and lacks the reddish lines.
Chanard’s Mud Snake has black markings lower on the sides. A scale count might be necessary to tell them apart.
Yellow-bellied Water Snake is uniformly dark above with no markings.
Rainbow Water Snake lacks any black markings.
Range: The Mekong Mud Snake is found in the lower Mekong drainage including eastern Thailand, southern Laos, Cambodia, and Vietnam. There is one population in the Chao Phraya River Basin in central Thailand.
Habitat: Slow-moving water bodies including ponds, ditches, rice paddies and canals. Is not known to leave the water.
Place in the ecosystem: Eats fish and frogs. Is eaten by larger snakes, large fish, monitors, and wading birds.
Danger to humans: Is a rear-fanged species and will bite when threatened but is not dangerous to humans.
Conservation status and threats: The Mekong Mud Snake appears to be common within its range. However, it is one of many snakes that is being harvested unsustainably in several regions, including Cambodia and Vietnam.
Interesting facts: The Mekong Mud Snake is almost entirely limited to the lower Mekong River Basin. For example, one study found the species to be incredibly common inside the Khorat Basin which feeds into the Mekong, yet entirely absent just outside of it. Snakes can often have strict range boundaries due to minor habitat differences, competition from other species, and historical patterns in how the species spread. In this case the Mekong Mud Snake likely has never spread north due to the more mountainous terrain in that direction, though it is not known why it is not found further to the west like other water snakes. It may have something to do with historic competition with Jagor’s Water Snake and Chanard’s Mud Snake which kept it from establishing itself in central Thailand.