Impact of Minimum Daily Dissolved Oxygen Concentration on Production Performance of Hybrid Female Channel Catfish x Male Blue Catfish

Hybrid catfish (. Channel Catfish Ictalurus punctatus x male Blue Catfish I. furcatus) were reared as single-batch crops during the growing season (June-September) of two years under two different dissolved oxygen (DO) regimes each year: (1) a high-DO (control) treatment with minimum daily DO maintained above 3.8 ppm in both years and (2) a low-DO (test) treatment with minimum DO maintained at 1.6 ppm in the first year and 1.3 ppm in the second year. Fish were fed daily to apparent satiation with a 32% protein commercial feed and harvested each year. In both years, dissolved oxygen concentration significantly impacted gross and net production, final fish weight, and mean fish weight gain due to reduced feed intake. Feed intake was reduced in the low-DO treatment by 26.6% in year 1 and 29.2% in year 2. Food conversion ratios averaged 1.83 overall and were not affected by minimum DO. Fish in high-DO treatments gained an average of 44% more weight (1.50 lb/fish) than fish in low-DO treatments (1.04 lb/fish). Initial weight at stocking also had a significant impact on weight gain: fish stocked at a 0.16-lb average weight (year 2) gained 37% more weight than fish stocked at a 0.11-lb average weight (year 1), even though the stocking rate of the larger fish was 50% higher. Hybrid catfish had less reduction in feed intake at reduced DO compared with reported values for Channel Catfish and Blue Catfish.