Experience of rearing larger mass fish material in the ponds of the IV<sup>th</sup> fish-breeding zone
The research paper covers substantiation of rearing of the larger mass fish material in the pond polyculture of the Volga region of the III-IV fish breeding zones, since stocking of ponds using standard mass of 20-25 g does not allow to meet consumer demand for fish products quality expressed as average weight. Rearing of fish products throughout three years to average weight of 1.0-2.5 kg increases its production costs considerably, especially in case of artificial water supply of ponds. In our tests, fish stocking material - larger mass fingerlings were reared using the method of sparse density stocking. The value of average mass of fingerlings depended on their yield per hectare of the water area and was for carps - 44.10-67.93 g, silver carps - 78.61-220.3 g, whereas the general fish productivity of ponds was from 1.31 to 1.49 t/hectare. The test of using fish stock material of various quality by farms of Saratov Region demonstrates that the use of sub-standard material of carp and silver carps allows to receive fish products with an average weight of 200-500 g. With a mass offish stock of 20-30 g - 700-800, and when stocking using the mass of 50 g the average mass offish products is 1500-2000 g.