Stingray, White Edged Freshwater (Himantura signifer)
The White Edged freshwater stingray in Thailand is an extremely rare member of the Dasyatidae family of fishes with ancient ancestors dating back to the Pleistocene Epoch (2.6 million years ago).
The White Edged freshwater stingray is found in only four river systems in the world namely the Kapuas River in Borneo, the Indragiri River in Sumatra, the Perak River in Peninsular Malaysia and the Chaophraya River in Thailand and its adjoining tributaries.
This freshwater stingray in Thailand is found in several tributaries of the Chaophraya River including the Nakon Nayok canal and adjoining waterways.
This freshwater stingray is found almost exclusively in freshwater environments but is capable of surviving in brackish water for short periods.
This freshwater stingray species is an extremely rare freshwater stingray that is easily identified by a distinctive delineated white band that lines the edge of the stingrays pectoral disc.
This distinctive white marking is also apparent in the stingrays whip like tail which is armed with two sharp venomous barbs.
The White Edged freshwater stingray displays a brown to grey colouration on its upper side with a band of rough dermal denticles along the centre of its back and is composed almost entirely of pure cartilage and has an extremely smooth underside with a small bow shaped mouth lined with crushing pads and gill slits.
The stingray has small eyes located on its upper side in front of large spiracles and is equipped with advanced electro-receptors called Ampullae de Lorenzini which allow it to actively hunt live prey by homing in on the electric signals given off by all living things.This inbuilt radar system which is similar to other shark species allows the White Edged freshwater stingray to keenly seek out prey buried in the muddy and sandy substrate.
The White Edged freshwater stingray is believed to attain a maximum width of 60cm and has been classified as being endangered by the IUCN.
Fishing for White Edged freshwater stingrays in Thailand is possible with small prawns and shrimps in the quieter canals and tributaries of the Chaophraya River.