Relations between environmental variables and fish standing crops were examined in 1972-73 as part of a Predator-Stocking-Evaluation of reservoirs, sponsored by the Reservoir Committee, Southern Division of the American Fisheries Society. High volumes of flow and increased water exchange rates in 1973 were associated with increases in fish standing crops and changes in the size structure of fish assemblages in some study reservoirs. Reservoirs with higher inherent water exchange rates also supported larger standing crops than those with lower exchange rates. However, highly variable responses of fish populations in different reservoirs to environmental change reflect the importance of other physicochemical and biological interactions not measured in this analysis. Combinations of environmental variables explained from 41 to 67% of the variation in selected standing crop components.