For the first time during the past 40 years we studied the structural characteristics of planktonic and benthic communities (phyto- and bacterial plankton, phytoperiphyton, meio- and macrozoobenthos, higher aquatic vegetation), and the food spectrum of fish in the rocky littoral zone of the Vygozerskoe impounding reservoir. We found a significant difference in the structure of these communities between the northern and southern parts of the reservoir. The maximum biomass of phytoplankton was recorded in Sennaya Bay – 6.5 mg/l, due to the development of the colonial diatom alga Tabellaria flocculosa, an indicator of low concentrations of nutrients and oligotrophic conditions. The relatively high biomasses of phytoperiphyton (green and blue-green algae) and macrophytes in the southern part of the reservoir evidence the eutrophication process. Benthic organisms are a food for perch, roach and whitefish, but the low biomass of meio- and macrozoobenthos (2–3 g/m²) in the littoral zone of the reservoir causes the fish to feed on a mixed diet, utilizing drift and planktonic crustaceans as a food.