Effect of Oxygen Management on Culture Performance of Channel Catfish in Earthen Ponds

Aeration allows for higher feeding rates and increased production of channel catfish Ictalurus punctatus in intensive and semi-intensive aquaculture systems. However, the effect of specific dissolved oxygen (DO) concentrations on various production parameters remains unknown. The purpose of this 2-year study was to determine the effect of daily minimum DO concentration on channel catfish production. Six 0.1-ha ponds were each equipped with three 0.37-kW (0.5-hp) aerators and one 0.37-kW circulator. Dissolved oxygen concentrations were monitored and recorded with a commercial oxygen monitor that also controlled aeration. During both years, aeration in the high-oxygen treatment was initiated when the DO concentration dropped below 5.0 mg/L (mean, 64% saturation from May to September); aeration in the low-oxygen treatment was initiated when the DO concentration dropped below 2.5 mg/L (32% saturation; 2001) or 1.5 mg/L (19% saturation; 2002). The minimum DO concentrations resulting from this aeration protocol differed somewhat from aerator set points. In the low-oxygen treatment, delaying aeration until the DO concentration dropped below 2.5 mg/L reduced feed consumption by 6% relative to the highoxygen treatment. Other production parameters were not significantly different. In 2002, when aeration was delayed until the DO concentration dropped below 1.5 mg/L, the low-oxygen treatment group exhibited reductions in food consumption (45% less than consumption by the high-oxygen treatment), average fish weight (31% less), and net production (54% less). Even at the high feeding rates of 2002 (maximum of 680 kg · ha-1 · d-1; 44,066 kg/ha total in one pond), other water quality variables were acceptable. Net production in the high-oxygen treatment in 2002 averaged 23,547 kg/ha, a potential record for channel catfish in earthen ponds. Neither the feed conversion ratio nor survival was significantly different between treatments in either year. While these results cannot be directly extrapolated to large commercial ponds, it appears that increased aeration may increase production well above current commercial levels