This study reports of biological efficiency of "The device of temperature compensation" (DTC) for cages used for growing juvenile rainbow trout (2 yrs) in high temperature water in Ladoga Lake. Two experimental cages, volume 125 m³, with trout (Parasalmo (Oncorhynhus) mykiss Walbaum) the initial body weight225 grams were prepared for summer grown study. We find that juvenile trout in cage without DTC located on the depth of5 m with pure oxygen saturation – 6 – 7 mg/l when the temperature of water surface increased to 20,0 – 22,7 º C. While in cage equipped with DTC trout found in all water column because temperature 12,7 – 14,0 º C was optimal and oxygen concentration 5,9 – 6,5 mg/l. Survival rate was 93,8 % and 54,9 % respectively. At the end of the experiment (day 90), the average body mass of the fish in cage with DTC was455 g compared to320 g in the ordinary cage. The difference in growth performance and survival rate illustrated expediency of the use of technologies to decrease water temperature and increase the concentration of oxygen in the water to the optimum value for growing trout in cages with DTC. The results of research show that DTC can be used in fish farm.