The paper provides an analysis of the abiotic aquatic environment factors that produce the greatest effect on the growth of rainbow trout in the first two years of cage breeding. Studies were carried out at two fish farms based in waterbodies in the Medvezhyegorsky District, Republic of Karelia – Lake Yelmozero and Svyatukha Bay of Lake Onego. The waterbodies differ in the nutrient status: Lake Yelmozero is oligotrophic and Svyatukha Bay is mesotrophic. We demonstrate that the hydrochemical parameters being nearly identical, the decisive factor for these facilities is the temperature, which is directly governed by the hydrological features of the waterbodies. Analysis of the data collected in this study showed that the rearing process being the same, the growth rates of trout in Svyatukha Bay were 1.5 higher than in Lake Yelmozero.