Treatise of biological problems of inland water bodies, especially from the practical point of view. Courses consist of the following chapters:  resoursces of inland water bodies;  the exploitation of their biological resources;  impact of the exploitation on the ecosystem;  principles of management and protection;  economical exploitation and protection;  restoration;  biomanipulation;  toxic substances;  principles of aquatic toxicology;  monitoring of inland water bodies;  water and mass balance. Estimation methods of the ecological status and restoration are the main topics.