The study focused on the species and taxonomic diversity of fish in the catchments of rivers Zimnyaya Zolotitsa and Soyana (White Sea-Kuloy plateau), exposed to indirect im pact from diamond mining in the Arkhangelsk Region. Faunal complex affiliations, ecological characteristics of nutrition and natural reproduction (spawning substrates and egg deposition methods) of the fish were revealed. The families with the greatest number of species were Coregonidae in the Zolotitsa catchment, and Cyprinidae in the Soyana catchment. All fish inhabiting the two catchments compared belonged to 5 faunal complexes, with a prevalence of arctic freshwater species in the Zolotitsa catchment, and boreal piedmont species in the Soyana catchment. In dietary terms, the species falls into four groups: plankton-feeders, benthos-feeders, predators (including the parasitic predation of lampreys), and euryphagous, the latter two quantitatively prevailing in both catchments. In terms of reproduction characteristics, the largest number of species in both the Zolotitsa and the Soyansa catchment spawn in stony-sandy bottom areas, being litho- and psammophiles in relation to the spawning substrate. The economic value of the fish fauna was determined, and rare, regionally red-listed fish species were identified. Data on the current composition of the fish fauna can be used as background information in a comprehensive assessment of the impact of mine-and-mill operations during industrial-scale development of diamond deposits on river ecosystems.