The paper defines the methods for maintenance of maximum density (Nmax) in respect of the freshwater crayfish (Astacus leptodactylus) fingerlings (larvae/juveniles), a prospective model organism for aquaculture. The question of optimal maintenance of the fingerlings has been addressed in the present study, considering the following parameters: (1) the ratio between the total area on which the fingerlings are being grown, and the area occupied by one individual, and (2) the planting density dependence on the specific growth rate of differently aged individuals (Cw). Analysis of our results shows that the Nmax values decrease significantly with the growth of individuals (4167, 2222 and 617 ind. m−2 for 30, 65 and 120 days old fingerlings, respectively). The values of Cw for individuals at the age of 30 days, however, do not depend on rearing density within the range of 300–1500 ind. m−2. A linear decrease in Cw is observed in density gradient for older ages. The density at which Cw becomes equal to zero is 3553 ind. m−2 for 65 days old fingerlings, and 1307 ind. m−2 for the 120 days old ones. The revealed differences (with respect to growth rates and planting densities in different age groups) may presumably be caused by the influence of the specific mechanisms of an intra-populational regulation, tenable with the conditions of high densities of fingerlings.
