In Russia the main stocks of Artemia cysts and their catching are concentrated in Western Siberia. According to long-term statistics, about 1100 tons of cysts on average are produced annually in raw weight, 180 tons from them are produced in Kurgan region and 140 tons are produced on the lake Medvezhye (about 2 % of the world's catch). Since 1925 the lake has been treated with sulfide-silt mud, the stocks of the mud consist of about 13 million m3. Since 1995 cysts have been harvested. On average during the catching period stocks of cysts were formed in the lake annually in the amount of 115 kg / ha, the catch was 24 kg/ha (21 % of the stocks). The residual density of cysts after catching is 10 kg / ha, which is necessary for the reproduction of Artemia population for the next season during the first generation. The average data have shown that 91 kg/ha of cysts remain in the biocenosis of the lake Medvezhye after catching, i.e. in 9 times more than the specified density. The main components which form therapeutic mud in the reservoir: brine, microalgae, crustaceans and Artemia cysts are analyzed in the article. The salinity of the brine in the lake Medvezhye was 110-320 g/dm3 in different years and it depended on the water content of the year. In the lake there is a small-cell phytoplankton which functions all year round. It is characterized by low indicators of biomass (0.05-16.6 mg/L, on average -1.5 mg/L), daily production (0.01-3.60 mgO2/L, on average -1.0 mgO2/L or 0.3 mgC/L) and high indicators of A/B and P/B coefficients. The annual production of phytoplankton on average was 8.39 t/ha in raw weight. Zooplankton and zoobenthos are represented mainly only by Artemia. The average crustacean biomass for the lake Medvezhye during the period 1995-2018 was 21.9 mg/L (219 kg/ha). Artemia production calculated in the period 2000-2003 was 315 kcal/m2/year. In general, the main components of the lake involved in the formation of therapeutic mud are phytoplankton, Artemia crustaceans, Artemia cysts. They have follow ratio - 8390: 2678: 115 kg / ha / year (75.0 % : 23.9 % : 1.1 %). The removal of cysts from the lake in the amount of 24 kg/ha (0.22 % of the biomass from all components) is negligible compared to the other components of the biocenosis.