Belarusian scientists analyze the causes of summer fish pestilence. Specialists of the Institute of Fisheries at the Academy of Sciences started control catches. Among the experimental fishing locations are the Zaslavskoye and Dubrovskoye reservoirs, the Ptich and Svisloch rivers. The use of the nets was agreed with the Ministry of Natural Resources. The results of the research will be analyzed at the laboratories of the Institute. To date, one of the reasons for the mass death of fish is called the lack of oxygen in reservoirs due to the heat and active algal blooming.