Experimental estimation of а temperature optimum in the juvenile of a freshwater fish species by method thermopreferendum

The description of a method allowing to define meaning of a temperature optimum for the juvenile fish is given. The thermopreferendum method is based on creating of experimental thermogradient conditions to fishes, in which they spontaneously choose a zone of a ecological-physiological optimum. The data on 21 species of freshwater fishes -meaning of final preferred temperatures for fingerlings and yearlings in a summer season of year are analyzed. The received results are urgent and are claimed both in theoretical and in the practical plan.