I. Lake Tanganyika and Its

The cichlid species flocks of the great East African lakes represent the most diverse assemblages of fresh-n'ater fishes in the world. Lake Tanganyika is by far the oldest of the three major East African rift lakes with an estimated age of about 9 to 12 million years (Cohen et al., 1993). Its geological history is relatively well known (reviewed in Tiercelin and Mondeguer, \997). The lake is formed of three basins which have been fused to one large lake about 5 to 6 million years ago. Seismic data show that about 200,000 (Tiercelin and Mondeguer, 7991) to 75,000 (Scholz and Rosendahl, 7988; C. A. Scholz personal communication) years ago the level of Lake Tanganyika dropped 600 m below its present levei, possibly even splitting the lake into three sublakes for several tens of thousands of years. This vi