The intensity of foraging is calculated by the formula: I = C/P year I — the intensity of foraging; C — the total diet of the population for a certain period of time; P = production of forage organisms for the same period of time. The intensity of forage organisms is considered to be high, with an indicator of more than 0.5, or 50%.

The different amount of food eaten is directly related to its caloric content and sometimes digestibility. The intensity of feed consumption depends on the condition of the fish. During spawning, many fish stop eating. The more well-fed eat less food than the less well-fed. Daily food intake also depends on the concentration of feeding fish. At the same time, juveniles at high concentrations feed more intensively than at low concentrations. In adult fish, on the contrary, the intensity of nutrition decreases at significant concentrations.