Nutritional and physical properties of the diet, management, and environment affect voluntary food consumption by channel catfish (lctalurus punctatus). Laboratory studies in which channel catfish were fed twice daily to satiation with semipurified diets containing various ratios of protein and digestihle. energy indicated that food intake was directly proportional to calorie density in the diet but independent of protein density until the protein percentage exceeded 45. Protein levels above 45% caused reduced food intake. Pond experiments in which channel catfish were fed to satiation twice daily, once daily, or on alternate days demonstrated that fish fed twice daily consumed the most food when water temperature was 26 C or greater, those fed once daily consumed the most food at 20-26 C, and those fed on alternate days consumed the most food when temperature declined below 20 C. channel catfish fed to satiation once dailr in ponds consumed 17% more of an extruded feed that had a mass density of 0.92 gl cm than one having a density of 0.83 g/cm J even though the former had a higher calorie density, indicating that stomach fill limited food intake.