Abstract Individual and group annual rations of Russian sturgeon Acipenser gueldenstaedtii are calculated on the basis of models describing the energy balance and dynamics of the number of fish generations with natural mortality depending on age. The structure of the energy balance and its separate components were studied. It is shown that the greatest amount of energy of consumed food by the population is spent on energy process. Individual rations of Russian sturgeon increase with age, whereas group rations decrease. The received results can be used to theoretically estimate the volumes of artificial and natural reproduction that provides the formation of stocks of Russian sturgeon in accordance with the forage productivity of the Caspian Sea.