Location: Warmwater Aquaculture Research UnitTitle: Effect of grading fingerling hybrid catfish (Channel Catfish X Blue Catfish) on growth, production, feed conversion, and foodfish size distribution.
Submitted to: North American Journal of Aquaculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/5/2018
Publication Date: N/A
Interpretive Summary: Hybrid catfish (a cross between female channel catfish and male blue catfish) are becoming increasingly popular with the US farm-raised catfish industry due to their faster growth. Hybrids now represent approximately 60% of the foodfish processed. The main disadvantage of hybrids is that they grow so fast that some fish outgrow the preferred size range of the processors. This study demonstrated that grading the fingerlings before stocking will result in a more uniform size of food fish at harvest without impacting net production, mean fish weight, or feed conversion.
Technical Abstract: Hybrid catfish production ponds often produce a wide size range of fish and payments to farmers may be reduced due to discounts for larger fish. This study was conducted to determine effect of grading hybrid catfish fingerlings on the size distribution of harvested foodfish. Three 0.25-acre ponds were stocked with 8,000/acre of ungraded fingerlings that averaged 0.05 lb (CV = 78.0%). Additional fingerlings were double-graded to produce fingerlings of the same average weight as the ungraded fingerlings (0.05 lbs) but with a reduced size variation (CV = 26.9%, P<0.01). Grading fingerlings had no significant effect on any production variable other than final size variation (CV = 48.2% and 26.1% for ungraded and graded fingerlings, respectively; P<0.01). Final mean weights were identical (1.1 lbs) and feed conversion ratios nearly identical (1.58 and 1.57) in both treatments. Survival and net production were similar between treatments. Overall, 13.5% of the ungraded fish and 1.2% of the graded fish were less than 0.5 lbs at harvest (P<0.01); 5.6% of the ungraded fish and 0.1% of the graded fish were larger than 2.0 lbs (P<0.01). Grading hybrid fingerlings is an effective means of decreasing foodfish size variability without impacting production efficiency.