A study was made to determine the level of dietary protein needed by channel catfish for optimum growth. The experimental work was conducted in the Farm Ponds Laboratory of Auburn University, Auburn, Alabama. Each of 40 stainless steel troughs was stocked with 25 six- to seven-inch fish. These fish were fed experimental diets at a rate of 2.5 percent of their body weight per day. Every 14 to 21 days from June 22 to September 3, 1961, the fish were re-weighed and their daily amount of food adjusted to the new weight. Eight purified diets were fed, each to five randomly-assigned troughs. These diets contained protein levels of 6.3, 15.8, 25.3 and 34.8 percent at carbohydrate levels of 9.8 and 18.6 percent. Samples of fish were randomly selected at the beginning and at the end of the experiment for carcass analysis. Growth for each diet was compared along with the amount of protein deposited in an effort to determine the level of protein which produced optimum growth. Statistical analyses indicated that of the levels tested a level of 25.3 percent protein produced optimum growth. Growth was obtained on the lowest level or 6.3 percent protein diet. The estimated maintenance requirement of protein for channel catfish in this experiment was 0.079 gram of protein per day per hundred grams of fish on the 9.3 percent carbohydrate diets and 0.029 gram of protein on the 18.6 percent carbohydrate diets. Based on this data, 0.23 gram of carbohydrate fed per hundred grams of fish would spare 0.05 gram of protein.
