Duckweed (Family Lemnaceae) was incorporated into 6 isocaloric diets which were fed for 10 weeks to channel catfish (Ictalurus punctatus) fingerlings in aquaria. Three diets contained surplus essential amino acids while utilizing duckweed at 0, 15, and 20 percent of the diet. Three other diets had the same levels of duckweed, but contained borderline levels of amino acids. No significant difference in mean weight gain per fish was found within each group of 3 diets. Feed conversion and kcal of energy required per g of weight gain were not statistically different for the fish fed the 6 diets.