Loaches and the environment in two provinces in Northern Vietnam

Abstract. During the last decades, agriculture activities in the mountainous northern provinces of Vietnam intensified drastically, and today rice fields occupy the complete valleys of local streams and rivers. Upstream of the fields, many dams were built mainly for irrigation purposes; sometimes stopping the flow through the lower courses of the creek completely. Illegal fishing with electro-fishing gears is a common way to improve food supply for local villagers. Larger rivers are impacted by non-selective fishing, gravel mining and pollution. These factors represent threats to the local fish communities, which typically include one or several species of loaches. With usage of electro-fishing gear and hand net we surveyed 16 localities of the river basins of the River Ky Cung and the River Bang Giang. Both rivers belong to the drainage area of the River Pearl in the provinces Lang Son and Cao Bang in Northern Vietnam. We focused on getting maximum number of fish species with special attention to loaches at each locality. Ten species of loaches were found; at least two of them represent undescribed species. The main conclusion is that the ichthyofauna of Northern Vietnam still holds a hidden diversity, but at the same time is under strong anthropogenic pressure, so that parts of the diversity may be lost soon.