Submitted to: Aquaculture America Conference
Publication Type: Abstract Only
Publication Acceptance Date: 11/10/2011
Publication Date: N/A
Technical Abstract: Year-old hybrid catfish were reared in 2008, 2009 and 2010 as single-batch crops under two different dissolved oxygen (DO) regimes each year; a high DO (control) treatment in which the minimum DO was maintained at 3.8-4.6 ppm during the growing season (June through September), and a low DO (test) treatment in which the DO was maintained at 1.3-1.6 ppm. Initial stocking rates/weights the three years were 16,000/acre at 0.14 lbs/fish, 8,000/acre at 0.11 lbs/fish, and 12,000/acre at 0.16 lb/fish. Fish were fed daily to apparent satiation with a 32% protein commercial floating feed and clean harvested at the end of each year. Mean weight gain averaged 1.40 and 1.06 lb/fish in the high and low DO treatments in 2008; 1.26 and 0.87 lbs/fish in the high and low DO treatments in 2009; and 1.73 and 1.20 lbs/fish in the high and low DO treatments in 2010. Gross and net production, final fish weight and mean fish weight gain were lower in the low DO treatments all three years due to reduced feed intake. Feed intake was reduced in the low DO treatments by 18.9%, 26.6% and 29.2% in the three years; however, the impact of low DO on feed intake of hybrid catfish was less than has been seen with channel catfish at comparable minimum DO concentrations. FCRs averaged 1.84 overall and were correlated with survival. With DO maintained at either control or test concentrations, stocking rates up to 16,000/acre had little impact on fish growth. We believe the main effect of higher fish densities seen in many previous pond studies has been reduced DO concentrations which affect feed intake. Over the three years, fish maintained at a higher minimum DO concentration gained an average of 40% more weight (1.46 lbs/fish gain in the high DO treatments, compared to 1.04 lbs/fish at low DO concentrations). Initial weight at stocking also had a significant impact on weight gain. Fish stocked at 0.16 lb average weight gained 37% more weight (1.73 lb/fish) than fish stocked at 0.11 lbs average weight (1.26 lb/fish) even though they were stocked at a higher rate.