Results of cage rearing of the whitefish (Coregonus lavaretus L.) and C. peled Gmel. obtained in the pelagic zone of the lake are better than those from the littoral where pressure of various parasites is strongly marked. Regardless of this trend, however, fish culture in cages placed in different lake zones should be regarded as a highly variable random process, its variability being a net result of both the variation in various environmental processes and interaction of different components of the ecosystem.