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Mekong River map courtesy WWF. |
Enigmatic loach (Ellopostoma mystax) by Kampol Udomrittiruj / WWF. |
The Mekong River flows nearly 2,800 miles through southeastern Asia, from Yunnan province in China via Vietnam, Thailand and Cambodia to the ocean. It provides a diverse range of habitats, ranging from fast-flowing upland waters to lakes. What makes the region particularly unusual, however, is that it was unaffected by the last ice age, and so species continued to thrive and diversify in this part of the world. As a result, the region is now home to one of the largest numbers of endemic species which are found nowhere else on the planet.
The World Widelife Fund (WWF) has recently published a report outlining the remarkable biodiversity that exists in the region. There are more than 1,300 species of fish present in the Mekong River basin, in habitats ranging from peaty swamps to limestone caves. These include the massive Mekong catfish (Pangasianodon gigas), which can grow to nearly 9 feet long, but there are still many others awaiting discovery.
Every survey of the river and its tributaries produces new finds. Between 1997 and 2007, there have been 279 unidentified species of fish found in these waters. Many are relatives of many familiar aquarium fish, including various bettas, cyprinids, catfish, gobies and loaches.
Typical of these is the so-called enigmatic loach (Ellopostoma mystax), which lives in shallow sandy areas of the river. Measuring in at just under 3 inches in length, it is restricted to the Tapi basin in Thailand. Its scientific name ‘mystax’ derives from the dark markings on the front of its snout which resemble a mustache.
However, one particular species from the Mekong River basin remained unidentified for 32 years after its initial discovery. The freshwater threadfish (Polynemus bidentatus) was collected in Vietnam during 1974, but only when scientists were reexamining the fish did they realize that it too was a previously unknown species.