Forage objects that are used by fish in the absence of basic food. Changes in the composition of food are observed in fish throughout the year. This is due to changes in the composition of forage organisms and in their availability. So, cod in the Barents Sea feeds mainly on herring and young fish in spring, and in winter in some areas even such planktonic organisms as combworms. And the forced food for the pelage is the fry of perch and roach, for the grouse - the nine-headed stickleback, for sturgeon - the grouse.