Lack of literature data relating to the parameters of drying the plant-fish feedstuffs in industrial hot-air and contact drum driers was the reason for un- dertaking this research. Its purpose was to determine the relationship between the input parameters of the drying operation and the dry weight content in plant-fish feeding concentrates. The knowledge of this relationship is a ne- cessary condition for a conscious control of the drying operation of such concentrates in the industrial conditions. In the tests, mashes were dried at a ratio of 3:1 (fish component: plant component. by weight), based on feed sprat preliminary ground to the particles equivalent in diameter to 3.5 mm, and wheat bran. For the changing sets of the values of the input parameters (temperature, time, filling degree of the drum with the mash, drum circumferential velocity and air flow velocity), the dry weight content was determined in the product. The results obtained allowed for the formulation of the relationship between the dry weight content in the product as a function of drying parameters grouped into dimen- sionless numbers.