Thai National Parks

Species of Thailand

South Asian bockadam

Cerberus rynchops, Johann Gottlob Theaenus Schneider, 1799

(In Thai: งูปากกว้างน้ำเค็ม, ngu paak guang naam kaem)

Cerberus rynchops, also known as the New Guinea bockadam, South Asian bockadam, bockadam snake, or dog-faced water snake, is a mildly venomous species of a snake in the family Homalopsidae. It is native to coastal waters of South and Southeast Asia. The species was re-delimited in 2012, allocating populations east and south of the west coast of Thailand to other species.

Ecology and behaviour

It is commonly found in mangroves, mudflats, streams, ponds, tidal pools, on algae patches, and has even been found burrowing into the mud. It is rear-fanged and is mildly venomous. An aquatic and nocturnal snake, it feeds mainly on fish and is known to consume eels.

In captivity, it is observed to move in a sidewinding direction on land. In the BBC series 'Life in Cold Blood' it was filmed adapting this sidewinding technique to jump across a mudflat in Singapore; up until then, no snakes were considered able to truly jump. It also has a prehensile tail that would suggest it could climb mangrove trees. It is now known to give birth to live young, numbering from 8 to 30, either in water or on land.

It is a quite docile, mild-tempered and a hardy snake; in recent years it has become a welcome addition to snake hobbyists in the Philippines. It also owes its popularity to its bright yellow to orange belly coloring, mostly of females. In the Philippines, particularly in the Central Visayas area, this snake is commonly known as the "tangkig".


The visibility of upper jaw, giving it a dog-like appearance. Head long and distinct from neck. Eyes small and beady, with rounded pupils. Dorsum dark gray, with faint dark blotches and a dark line along the sides of the head, across the eyes. Center cream with two distinct rows of large, diffuse dark gray spots.

Scales are distinctly keeled. Midbody scale rows 21-25. Ventrals 132-160. Subcaudals 49-72.

Distribution and habitat

This is a saltwater-tolerant species found in India (including Andaman and Nicobar Islands), Sri Lanka, North Western Pakistan Khyber Pakhtunkhwa, Bangladesh, Myanmar, the Philippines, and Thailand. The eastern limit of its distribution with Cerberus schneiderii is uncertain.

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Scientific classification

Cerberus rynchops

Common names

  • Thai: งูปากกว้างน้ำเค็ม, ngu paak guang naam kaem


  • Cerberus rynchops, John C. Murphy & Harold K. Voris (2014)
  • Cerberus rynchops, Van Stanley Bartholomew Wallach et al. (2014)
  • Cerberus rhynchops, T. S. N. Murthy (2010)
  • Cerberus rynchops, Harold Cogger (2000)
  • Cerberus rynchops, Merel J. Cox et al. (1998)
  • Cerberus rynchops, Ulrich Manthey & Wolfgang Grossmann (1997)
  • Cerberus rhynchops, John Roscoe Hendrickson (1966)
  • Cerberus rynchops rynchops, Arthur Loveridge (1948)
  • Cerberus rynchops, Malcolm Arthur Smith (1943)
  • Cerberus rynchops, Malcolm Arthur Smith (1930)

Conservation status

Least Concern (IUCN3.1)

Least Concern (IUCN3.1)


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Cerberus rynchops - Mu Ko Ranong NP
Cerberus rynchops - Mu Ko Ranong NP
Cerberus rynchops - Mu Ko Ranong NP

Range Map

Distribution map of South Asian bockadam, Cerberus rynchops in Thailand
  • Kra Buri District, Ranong
  • Mu Ko Ranong National Park
Range map of Cerberus rynchops in Thailand