The single 24-hour feeding chronology study indicated that subadult and adult catfish fed heavily during the daylight hours although some feeding also occurred in the night. The major foods eaten by subadults and adults differed over the 24-hour period. Fishes formed the hulk of the diet at 0600 and 0900 hours and insects at 0400 and 2400 hours; whereas the zooplankton was the principal food at other periods. The presence of large amounts of detritus (sand and mud) during the times of heavy feeding indicated near-bottom feed' in habits. Stomach contents of 798 subadult and adult channel catfish (122 to 270 mm fork were length) collected from July to November, 1966 in Conowingo Reservoir were examined. Stomachs of 183 young catfish (35 to 83 mm) collected in August and September were also analyzed. By weight and on the basis percentage frequency of occurrence zooplankton was the principal food of catfish of all sizes. Fishes were important in the diet of subadults and adults only in August and October. Amphipods comprised an important segment of the diet of subadults and adults only in November. Insects and algae were less important.