Abstract
Data on total weight and standard length of freshwater bream and perch, two of the most abundant fish species in the Volga River basin, were collected monthly from April 2016 to May 2017. Fish were caught using gill-nets with 50 and 80 mm mesh sizes. Linear regression analysis of log-transformed values was performed. Regression slope and intercept were used to obtain length-weight relationships and mean condition factors. The data can be used for calculation of the relative weights of given species and further efforts to develop a mathematical model for the Volga River ecosystem.