The aim of this study is to determine the egg and larval growth performance of brown trout (Salmo trutta sp.) at a constant high water temperature under commercial farm conditions. Eggs were taken from 450 female broodstocks with an average weight of 5.09±0.29 kg. The eggs placed in the incubators were observed on the 14th day and kept at a constant temperature of 12.5°C. Then larvae began to hatch on the 29th day and all the eggs were fully hatched by the 31st day. The incubation period was determined as 350 days /°C. In the study, an average survival rate was determined as 21.07%±5.16% until the end of the larval stage. A significant relationship was found between the rate of eggs that hatched and the survival rate after the larval period had ended (p<0.05). After 120 days of larval feeding, larvae weighing 0.15 g reached 9.26±1.13 g. During this period, the feed conversion rate (FCR) and specific growth rate (SGR) values were determined as 1.21±0.09 and 1.23±0.72 respectively.