The Severnaya Dvina is rightfully considered one of the largest rivers in Russia’s European North and is the main catchment for fisheries in the Arkhangelsk Region. Its lower course is under enormous pressure from numerous pollution sources located along its tributaries and in the estuary. This situation leads to changes in fish habitat conditions, their species diversity, as well as biological parameters, population structure, population dynamics, and stock. This article presents the results of a study of the fish population in the estuarine region of the Severnaya Dvina in 2019 by classical ichthyological research methods using passive (stake nets) and active (draft nets) fishing gear. The species composition and taxonomic diversity of the fish fauna are presented. We determined the affiliations of the fish with faunistic complexes and ecological groups differing in dietary and natural reproduction characteristics (spawning substrates, egg-laying methods, and spawning periods). The economic significance of the fish fauna was assessed, rare and scant fish species listed in the regional Red Data Book were identified. The biological characteristics (length-weight structure, age and sexual composition) of the populations of the main commercial fish species are described. The dietary habits of the two most important species groups, coregonids (whitefish) and cyprinids (bream), are considered. The fish species diversity in the Severnaya Dvina estuary is quite high. The list totals 36 fish species. The biological characteristics of the fish were found to be within the average range for the given species. The commercially important whitefish and bream are benthos feeders (potential competitors for food). But the tension of this competition is reduced due to their different dominant feed items.