Province of Yunnan in China

The dry season fish fauna of the Mekong River is dominated by species of carp (Cyprinidae; 54%), catfish (Siluridae, Clariidae, Schilbeidae, Bagridae, Sisoridae and Akysidae; 19%) and murrels (Chanidae and Ophicephalidae; 8%). The remaining 19% consist of featherbacks (Notopteridae), herring (Clupeidae), climbing perch and gouramis (Anabantidae) and other miscellaneous groups. Some 85-95% of the freshwater fish populations in the Mekong basin follow the inundation spawning pattern, undertaking lateral migrations from the mainstream and tributaries into the inundation zones to spawn and rear young between July and September (Pantulu, 1986b).One of the most remarkable of the Mekong's endemic fishes is the Giant Catfish Pangasianodon gigas. This species, which can attain a length of over three metres and a weight of 250-300 kg, is a main channel migrant, reportedly migrating over a distance of several thousand kilometres from the region of Phnom Penh to spawning grounds in the province of Yunnan in China. It was once quite common in the lower stretches of the Mekong, with several thousand being caught each year below Khone Falls. However, over-exploitation of existing stocks and environmental changes consequent on development activities in the region have contributed to a serious decline in the population, and the species is now almost extinct below Pak Sane in northern Laos (Pantulu, l986b).