Effects of Feeding Rate on Water Quality, Production of Channel Catfish, and Economic Returns

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Abstract
Channel catfish (Ictalurus punctatus) were stocked in 0.02 to 0.04‐hectare ponds without aeration at three rates (4,942, 10,007, and 20,385 fish per hectare) and fed daily. Fish averaged 12 cm total length and 10 g at stocking. Each treatment was replicated six times. Maximum feeding rates of 34, 56, and 78 kg/hectare, respectively, were reached by midsummer. In the low treatment, no dissolved oxygen (DO) problems occurred, and survival was 99%. In the medium treatment, DO at dawn frequently fell below 2.0 mg/liter and some fish suffocated during an oxygen depletion in one pond; however, survival averaged 93%. In the high treatment, DO at dawn was usually below 2.0 mg/liter in August and September. Fish mortalities resulted from DO depletion in three ponds of the high treatment, but survival averaged 83%. Nitrite‐nitrogen and un‐ionized ammonia never reached concentrations recognized to be lethal to channel catfish in any of the treatments. However, concentrations of un‐ionized ammonia were possibly high enough to have adversely affected growth. Even though the average weight of individual fish decreased, harvest weight of fish increased from low to high treatment. The low treatment produced an average of 2,990 kg/hectare of fish and a net economic gain of /1,136. The medium treatment produced an average 4,100 kg/hectare for a net gain of /1,303. The high treatment produced an average of 4,860 kg per hectare, but a net gain of only $671.