The paper presents the results of studies on spined loach, Cobitis taenia (L.) diet in Zegrzyński Dam Reservoir. Food composition of the fish collected at four stations was analysed and compared. The stations differed as to the environmental conditions. Changes of diet components in particular months were described for two sampling stations, habitat conditions preferred by spined loach were described on the basis of the results and the literature data. A description was also given of its feeding grounds in the reservoir, and of the food of this fish in different places of its range of occurrence.