On example of wild and hatchery (cultivated in ponds and pools) young Russian sturgeons and white salmons, it is shown that fishes cultivated in more complicated ecological conditions (in natural reservoir in comparison to artificial and in ponds in comparison to pools) have greater sizes of CNS structures connected with the development of the analyzer leading in the life of this species (the midbrain--in white salmon, the forebrain--in sturgeon) and are characterized by a higher content of DNA in the brain and of RNA at the unit of DNA. This testified to more intensive processes of replication and transcription in CNS cells, more expressed manifestation of motor activity and higher parameters of elaboration and retention of a new habit. All this points to the necessity of enrichment of the medium in the hatchery reservoirs and the expediency of using of genetic-neurobiological criteria of hatching the young.