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The effect of photoperiod on the growth of juvenile Siberian sturgeon Acipenser baerii has been studied in aquarium experiments. The maximum growth rate of juvenile Siberian sturgeon was observed under 12, 16, and 24 h photoperiods. This was accompanied by high respiratory rate and total food consumption and conversion. Rearing in the dark significantly decreased these indices. The hematological indices were within the normal range under optimal photoperiodic conditions. Pronounced neutrophilia and leukopenia were observed in the absence of light.

The levels of chromosome mutations in hemopoietic cells of various fish from water bodies near the Noril'sk mining and smelting complex were estimated by the micronucleus test. In some cases very high frequencies of erythrocytes with micronuclei were observed in fish inhabiting highly polluted water bodies. On the whole, the number of cells with chromosome aberrations was within the limits of spontaneous mutagenesis. Marked species-specific, seasonal and local differences were found in the frequency of erythrocytes with micronuclei. The problems related to the influence of chemical pollutants on fish are discussed.

By means of polyacrylamide gel disc-electrophoresis studies have been made on a serum proteins of the kaluga Huso dauricus and Amur sturgeon Asipenser schrencki. High electrophoretic heterogeneity (18--23 components) of serum proteins of both species was demonstrated together with ecological peculiarities of fractional composition of these proteins as compared to those in Caspian sturgeons. The described high heterogeneity of serum proteins in the ganoid fishes is particularly interesting from the standpoint of evolution of fractional composition of proteins in vertebrates. Presumably, high heterogeneity of serum proteins in the ganoids (practically comparable to that in higher vertebrates and man) is necessary for successful work of the most important biochemical system of the blood at all stages of evolutionary development of vertebrates, being of rather ancient origin.