Submitted to: Aquaculture North America
Publication Type: Trade Journal
Publication Acceptance Date: 9/11/2012
Publication Date: 1/5/2013
Citation: Green, B.W. 2013. Growing stocker channel catfish in a biofloc technology production system. Aquaculture North America. 4:24. Interpretive Summary:
Technical Abstract: Biofloc technology (BFT), or mixed suspended-growth, production systems are being used more frequently worldwide for culturing various aquatic animals because of the high yields that are possible. In an outdoor BFT production system, a complex of living organisms is closely associated with particulate organic matter and is maintained in suspension by continuous aeration. Channel catfish production ponds in the U.S. increasingly are being stocked with 114- to 151-gram 'stocker' catfish instead of 25- to 35-gram fingerlings. Nearly 57% of catfish stocked into production ponds were stocker catfish according to the most-recent data available from the USDA. Because food-size catfish can be produced in a BFT production system, we undertook a study to test the effect of three stocking densities (1.4, 1.8, or 2.3 kilogram per cubic meter) on rearing fingerling channel catfish to stocker size in a BFT production system. Stocker-size channel catfish were harvested from all treatments. Net fish yield increased linearly as stocking density increased and was 3.5, 4.1, or 4.8 kilograms per cubic meter at the 1.4, 1.8, or 2.3 kilogram per cubic meter stocking rate, respectively. By comparison, in pond culture somewhat smaller fingerlings are stocked in ponds at 3.6 – 10.9 fish per square meter with net yield ranging from 0.3 – 0.9 kilograms per cubic meter of stockers that average 165 grams per fish. In this study, high feeding rates (87, 112, and 132 grams per cubic meter per day for the low to high stocking densities) were sustained from mid-July through the end of September. These feeding rates were equivalent to 650 to 974 pounds per acre per day in earthen ponds. Through digestion of consumed feed, these intensively fed fish excreted high quantities of nitrogen and phosphorus during this study. Algal uptake and bacterial transformation of this excreted nitrogen limited the accumulation of the toxic metabolite, ammonia-nitrogen.