The Crab-eating Water Snake, or Whitebelly Mangrove Snake as it is called in Australia, confines itself mainly to tidal habitats, where it preys on small fish and crabs. In particular it is locally common in mangroves.

There are several colour variations ranging from brown or grey with black spots, to purplish-black. The belly is pale in colour. The jaw is recessed under the head, and the eyes positioned towards the top of the head.

It is wide-ranging from India, Bangladesh, Burma and Thailand down through the Malay Peninsular through all the larger islands of Indonesia. In the extreme east of its range it can be seen in New Guinea and northern Australia. 

Family : COLUBRIDAE
Species : Fordonia leocobalia
Maximum Size : 95 cm

References : H1, H3

Link : Aquatic Snakes of Southeast Asia, Field Museum of Natural History ... follow this link