Three alpine lakes (Oiskoe, Karovoe, Raduzhnoe) of mountain range “Ergaki” were sampled in 11-15 September 2008. Species (taxonomic) composition, number of species, density and biomass of phytoplankton and zooplankton, phytobenthos and zoobenthos of each lake were studied for the first time. Coefficients of species similarity of plankton and benthos assemblages between lakes were calculated. Results of test fishing in the lake Oiskoe are presented. As found, species diversity of plankton and benthos assemblages of the lakes were not great and the lowest one was in the fishless lake Karovoe; species composition similarities between lakes were rather low (0.09-0.40). Biota of the lakes in general consists of species with widespread distribution, with the exception of some species, particularly Alona werestschagini Sinev known (in Russia) from Altai and north of Europe and Arctodiaptomus dahuricus Borutzky known from Transbaikalia. Thus areal of this species is expanded. (The latter would be new related species). Despite of low density and biomass of phyto- and zooplankton (level of oligotrophic lakes) and low or moderate zoobenthos biomass (oligotrophic-mesotrophic level) catch individuals of fish Thymallus arcticus Pallas were fat (mark 3-4) and their guts were filled. Apparently food supply is sufficient for good fitness of the grayling population.