The common keelback (Xenochrophis flavipunctata) is a snake

Snake

Snakes are elongate, legless, carnivorous reptiles of the suborder Serpentes that can be distinguished from legless lizards by their lack of eyelids and external ears. Like all squamates, snakes are ectothermic, amniote vertebrates covered in overlapping scales...

 of the family Colubridae. It is found mainly in marshy and waterlogged places (drains,sewage system, ponds etc.).

It is a mildly venomous (rear-fanged) snake and feeds mainly on frogs, toads and small fishes.

It is very common in northeast India

India

India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...

, in the state of Assam

Assam

Assam , also, rarely, Assam Valley and formerly the Assam Province , is a northeastern state of India and is one of the most culturally and geographically distinct regions of the country...

.

In Bengali

Bengali language

Bengali or Bangla is an eastern Indo-Aryan language. It is native to the region of eastern South Asia known as Bengal, which comprises present day Bangladesh, the Indian state of West Bengal, and parts of the Indian states of Tripura and Assam. It is written with the Bengali script...

, it is called "Jol dhora". It has a blackish dorsal portion, and its belly is white.