PUBLISHED REPORTS HAVE SHOWN THAT THE OPTIMUM LEVEL OF PROTEIN IN FEEDS FOR GROWTH OF INTENSIVELY CULTURED CHANNEL CATFISH HAS RANGED FROM 25 TO 46 PERCENT. THE FIGURES ARE BASED ON THE SPECIFIC PERCENTAGES OF PROTEIN FELT BEST FOR CATFISH GROWTH UNDER THE PARTICULAR EXPERIMENTAL CONDITIONS. THE MOST IMPORTANT FACTORS AFFECTING THESE GROWTH RESPONSES OF CHANNEL CATFISH WHEN FED FEEDS CONTAINING VARIABLE LEVELS OF CRUDE PROTEIN, BASED ON SEVERAL EXPERIMENTS, ARE DISCUSSED IN THIS REPORT. THESE FACTORS ARE: 1) SIZE OF FISH, 2) TEMPERATURE, 3) NATURAL FOOD AVAILABLE, 4) AMOUNT OF SUPPLEMENTAL RATION, 5) AMOUNT OF NON-PROTEIN ENERGY IN DIET, AND 6) QUALITY OF PROTEIN. THERE ARE OTHERS (NOT EXAMINED HERE), SUCH AS PHYSICAL PROPERTIES OF THE FEED (DIGESTIBILITY, FOR EXAMPLE), VARIOUS STRESSES ON THE FISH, AND THE LIST COULD BE CONTINUED. BUT EACH OF THESE MUST BE CONSIDERED WHEN INTERPRETING RESEARCH DATA OR DEVELOPING PRODUCTIVE DIETS IN WHICH QUANTITATIVE PROTEIN REQUIREMENTS OF CHANNEL CATFISH ARE CONCERNED.