Hypsiscopus plumbea

Yellow-bellied Water Snake Hypsiscopus plumbea Enhydris plumbea coiled to strike
Yellow-bellied Water Snake found on road near ponds in Phayao Province
Third Rice Paddy Snake Hypsiscopus plumbea Enhydris plumbea from same spot
Another Yellow-bellied Water Snake in Phayao Province
Yellow-bellied Water Snake Hypsiscopus plumbea Enhydris plumbea
Yellow-bellied Water Snake found in mud in Phayao Province
Yellow-bellied Water Snake Hypsiscopus plumbea Enhydris plumbea
Yellow-bellied Water Snake found under fish pond rock in Kanchanaburi Province
Rice Paddy Snake Hypsiscopus plumbea Enhydris plumbea nostrils and eyes
Close-up of Yellow-bellied Water Snake
Two Gray Water Snakes Hypsiscopus plumbea Enhydris plumbea
Two Yellow-bellied Water Snakes found under rock in Laos
plumbeous water snake Hypsiscopus plumbea enhydris plumbea
Yellow-bellied Water Snake in Vietnam (photo by Eduard Galoyan)
Yellow-bellied Water Snake Hong Kong eating frog enhydris plumbea
Yellow-bellied Water Snake eating frog in Hong Kong (photo by Anne Devan-Song)
Yellow-bellied Water Snake Hypsiscopus plumbea  Kevin Messenger China 1
Yellow-bellied Water Snakes in China (photo by Kevin Messenger)
rice paddy snake Enhydris plumbea  Kevin Messenger China
Yellow-bellied Water Snake showing unusual ventral color (photo by Kevin Messenger)

English name: Yellow-bellied Water Snake (aka: “Plumbeous Water Snake” or “Rice Paddy Snake”)
Scientific name: Hypsiscopus plumbea (formerly Enhydris plumbea)
Thai name: Ngu Pling

Description: To 77cm long. This small water snake has a moderately broad head and smooth scales. It is uniformly dark above with a pale cream to yellow underbelly.

Similar Species: Rainbow Water Snake has a smaller head and colored lines going down its body.
Jagor’s Water Snake has small dark blotches down its sides.
Chanard’s Mud Snake has a pale line down its side and a row of small dark dots above the line.
Sunbeam Snake is iridescent, has a narrow wedge-shaped head, and is whitish-gray on the bottom.
Red-tailed Pipe Snake has a small head and a barred underbelly.
Yellow-striped Caecilian lacks scales, has yellow stripes on the side rather than a yellow belly, and has a distinctly non-snake-like head.

Habitat: Slow-moving rivers, ponds, swamps, rice paddies, and other wetland habitats with stagnant water. Forages from dusk until dawn. Found on land more often than other water snakes, but rarely far from the water.

Place in the ecosystem: Feeds on fish and frogs. Eaten by larger snakes, large fish, monitors, and wading birds.

Danger to humans: The Yellow-bellied Water Snake will aggressively strike when cornered on land, but its small size keeps it from being able to inflict much damage. While it is a rear-fanged snake with some venom, the venom has a limited effect on humans, possibly leading to some swelling in the worst cases.

Conservation status and threats: No known conservation issues. This is a common species in Thailand, though its population in Taiwan is endangered.

Interesting facts: Yellow-bellied Water Snakes are excellent swimmers but move awkwardly on land. When faced with a threat on land, they will sometimes flip their bodies up into the air and backwards with a reverse-striking motion, propelling themselves erratically towards the water.

References:
Snakes of Taiwan: Enhydris plumbea
Reptiles of Hong Kong: Enhydris plumbea
The IUCN Red List: Enhydris plumbea
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