Location: Warmwater Aquaculture Research UnitTitle: Effect of graded fingerlings on hybrid catfish food fish size distribution
Submitted to: Aquaculture America Conference
Publication Type: Abstract Only
Publication Acceptance Date: 8/27/2016
Publication Date: 2/19/2017
Citation: Torrans, E.L., Ott, B.D. 2017. Effect of graded fingerlings on hybrid catfish food fish size distribution. Aquaculture America Conference. P. 469.
Technical Abstract: It is not unusual to have both 0.5 lb and 5 lb fish harvested from a single-batch hybrid catfish production pond at the end of the growing season. When that happens, farmers may be docked for fish that are either larger or smaller than the processor’s preferred size range. This study was conducted to determine the impact of grading fingerlings on the size distribution of food fish produced in a single-batch system. Three 0.25-acre earthen ponds were stocked with 8,000/acre of ungraded fingerlings on April 23. The fish were individually counted and mass-weighed, averaging 0.0498 lb (49.8 lbs/1000). The remaining fingerlings were double-graded to produce fingerlings of the approximate same average weight (52.5 lbs/1000) but with a reduced size variation (CV = 78% and 27% for the ungraded and graded fingerlings, respectively). The fish were first fed on May 29 and harvested on October 14-16. Grading fingerlings had no significant effect on any production parameter except for final size variation. Final mean fish weight (1.1 lbs) and FCR (1.58:1) was identical in both treatments. Survival and net production were not significantly different among treatments. For the purpose of comparison, we established an arbitrary “preferred size range” at harvest of 1.0-2.0 lbs. Overall, 41.5% of the ungraded fish and 28.1% of the graded fish were less than 1.0 lb at harvest (P=0.18). However 5.8% of the ungraded fish and 0.16% of the graded fish were larger than 2.0 lb (P=0.01). Grading hybrid fingerlings is an effective means of decreasing food fish size variability without impacting production efficiency.