The effect of dietary fiber level on growth and carcass composition of channel catfish and on pond water quality was studied by feeding fingerlings (30 per 20 m2pond) practical type feeds that contained identical nutrient components but graded levels of fiber ranging from 2 to 20%. After 200 days, fish fed the 2%-fiber feed had gained 3,132 kg/hectare; this was significantly (P < 0.05) more than fish fed the 14%-fiber feed (2,468 kg/hectare) or 20%-fiber feed (2,532 kg/hectare), but not the 8%-fiber feed (2,705 kg/hectare). Fiber level had no significant effect on composition or dress-out percentage of the carcasses. In the last 30 to 60 days, the ponds receiving the higher fiber-diets showed lower dissolved oxygen than the others. Although previous work has indicated that added cellulose is beneficial in purified fish diets, results from this study suggest that fiber provides no nutritional benefit in production-type feeds for channel catfish and when fed in large amounts may lower water quality.