In this study, over 20 fishers or fishing families using multiple seasonal gears on the southern end of Khone Island and the adjacent southern end of Sadam Island (mainstream Mekong River, Southern Lao PDR) were monitored between 1993 and 1999. Both locations are just below the Khone Falls fault line, and just north of the border with Cambodia. The use of the artisanal fishing gears in the Khone Falls are described, new information about thepossible migration patterns of 110 Mekong fish taxa is provided, hydrological triggers of fish migrations are detailed, and the crucial role of deep-water pools in the mainstream Mekong River as refuges for fish in the dry season is demonstrated. The overall objective of this study is to contribute to biodiversity conservation and the sustainable management of inland fisheries in the Khone Falls, a zone of major ecological and livelihood importance in Laos and in the Mekong River Basin.