Thai National Parks

Reptiles of Thailand

Species of Thailand

Gerard's water snake

Binomial name: Gerarda prevostiana (Joseph Fortuné Théodore Eydoux & Paul Gervais, 1822)

Gerarda prevostiana, commonly known as Gerard's water snake or the cat-eyed water snake, is a species of water snake endemic to Asia. It is the only species in the genus Gerarda.


The generic name, Gerarda, is in honor of someone named "Gerard". Unfortunately, Gray, who named the genus in 1849, did not specify whom he was honoring. Two possibilities are Adam Gerard or Rev. Gerard R. Smith, both of whom sent specimens of reptiles to Gray at the British Museum.

The specific name, prevostiana, is in honor of French naturalist and illustrator Florent Prévost.


G. prevostiana feed almost exclusively on crabs, which they tear into bite-sized pieces by pulling them through their coils, in contrast to most other snakes which swallow their prey whole.


Frontal a little longer than broad, shorter than its distance from the end of the snout, or than the parietals; loreal slightly longer than deep, a little smaller than the nasal; one preocular and two postoculars; temporals 1+2; upper labials 8, fourth entering the eye; 4 lower labials in contact with the anterior chin shields, which are much larger than the posterior. Dorsal scales in 17 rows at midbody. Ventrals 146–158; anal divided; subcaudals 31–34.

Uniform dark olive above; three outer rows of scales whitish; upper lip white, rostral dark olive; ventrals and subcaudals whitish, with dark edges.

Total length 41 cm (16 inches); tail 5 cm (2 inches).


G. prevostiana is found in India, Myanmar (= Burma), Sri Lanka, Thailand, Philippine Islands (Mindanao), Bangladesh, west Malaysia, and Singapore.

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Scientific classification

Gerarda prevostiana

Common names

  • German: Katzenaugen-Wassertrugnatter
  • English: Gerard's water snake, Cat-eyed water snake, Glossy marsh snake
  • Thai: งูปลาตาแมว


  • Gerarda prevostiana, John C. Murphy & Harold Knight Voris (2014)
  • Gerardia prevostiana, R.C. Sharma (2004)
  • Gerarda prevostiana, Merel J. Cox et al. (1998)
  • Gerarda prevostiana, Ulrich Manthey & Wolfgang Grossmann (1997)
  • Gerardia prevostianus, Indraneil Das (1996)
  • Gerardia prevostiana, Malcolm Arthur Smith (1943)
  • Gerardia prevostiana, Frank Wall (1921)
  • Gerardia prevostiana, Frank Wall (1905)
  • Gerardia sic prevostiana, George Albert Boulenger (1890)
  • Heleophis flavescens, Fritz Müller (1884)
  • Helipophis flavescens, Fritz Müller (1884)
  • Gerarda prevostiana, Edward Drinker Cope (1862)
  • Campylodon prevostianum, André Marie Constant Duméril & Gabriel Bibron (1854)
  • Campylodon prevostianum, André Marie Constant Duméril & Gabriel Bibron (1854)
  • Gerarda bicolor, John Edward Gray (1849)
  • Coluber (Homalopsis) prevostianus, Joseph Fortuné Théodore Eydoux & François Louis Paul Gervaise (1837)
  • Coluber prevostianus, Joseph Fortuné Théodore Eydoux & François Louis Paul Gervaise (1822)

Gerard's water snake is found in following locations in Thailand

Please note that this non-official list is not complete nor necessarily accurate. This list is a summary of checklists from other websites, blogs, publications, photo/videos published on various websites or our own findings. We appreciate your contributions with photo proof.

  • Chonburi Coast

Conservation status

Least Concern (IUCN3.1)

Least Concern (IUCN3.1)

No photo for this species yet

Distribution map of Gerard's water snake, Gerarda prevostiana in Thailand
  • Chonburi Coast

Range map of Gerarda prevostiana in Thailand

Important note; our range maps are generated automatically based on very limited data we have about the protected sites, the data is not necessarily accurate. Please help us to improve our range maps by sharing your findings/knowledge.