Summary.The food of salmon parr in the Dee and its tributaries has been studied for two years. Comparison of stomach‐contents with the results of field collections shows that the fishes are indiscriminately carnivorous, and that their diet varies strictly in accordance with the number and relative accessibility of species present in the rivers. The sub‐äerial element in the food is important, especially in autumn, when leaf‐eating tree‐parasites fall into the rivers as the leaves decay and are swallowed in considerable numbers. Encouragement of the growth of riparian trees and shrubs is thus desirable.There is a marked seasonal cycle in feeding, which accurately corresponds with the records of fluctuations in growth derived from scale‐readings. This seasonal cycle seems to be directly dependent upon the life‐histories of the various food‐organisms, which determine their availability to the fishes: in the opinion of the writer there is no evidence of loss of appetite at any season, but merely of variations