Submitted to: Catfish Farmers of America Research Symposium
Publication Type: Abstract Only
Publication Acceptance Date: 12/16/2011
Publication Date: 2/16/2012
Citation: Torrans, E.L., Ott, B.D. 2012. Effect of DO concentration, size of stockers, and density on growth and production of hybrid catfish. Catfish Farmers of America Research Symposium. P.16.
Technical Abstract: Year-old hybrid catfish were reared in 2008, 2009 and 2010 as single-batch crops under either a high or low dissolved oxygen (DO) regime each year. 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 satiation with a 32% protein feed and clean harvested at the end of each year. Gross and net production, final fish weight and mean 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 in previous studies with channel catfish at comparable minimum DO concentrations. 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 2009; and 1.73 and 1.20 lbs/fish in 2010. Overall, fish maintained at a higher 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 50% higher rate. FCRs averaged 1.84 overall and were loosely correlated with survival. Surprisingly, stocking rates up to 16,000/acre had no negative impact on fish growth. We believe the main direct effect of higher fish densities typically seen in warmwater ponds has been reduced DO concentrations resulting from the higher feeding rates, and these lower DO concentrations do affect feed intake and growth. We believe that with adequate aeration, hybrids can be grown at densities up to 16,000/acre without impacting growth; increased net gain/foodfish size can best be realized by stocking larger fingerlings and maintaining DO adequate concentrations, not reducing fish density.