2011 Annual Report
Stocking catfish fry. Holding catfish fry in the hatchery and feeding commercial starter diets for a week or more is the common practice in commercial catfish farming. Holding fish in the hatchery is, however, labor intensive and expensive. Previous studies in small ponds showed that fry could be stocked into nursery ponds at very young ages with no reduction in survival or growth. If this is true when larger ponds (as on commercial farms) are used, reducing residence time in the hatchery would reduce costs and benefit fingerling producers. However, ARS and Mississippi State University scientists at the National Warmwater Aquaculture Center, Stoneville, MS, showed that stocking fry early leads to poor survival. Stocking hatchery-fed fry resulted in 41.6% survival, stocking swim-up fry resulted in 7.1% survival, and stocking sac fry resulted in 4.5% survival. Without some means of protecting fry from predators, early stocking is too risky for commercial producers.
Co-stocking planktivorous fish. Co-stocking small planktivorous fish could increase efficiency of channel catfish production by providing natural forage and reducing cyanobacteria originating off-flavors. Scientists at the National Warmwater Aquaculture Center, Stoneville, MS, evaluated the effects of co-stocking fathead minnows and threadfin shad with channel catfish. Stocking fathead minnows was not beneficial to water quality or fish production, but the filter-feeding habits of threadfin shad changed the plankton community beneficially by reducing the abundance of blue-green algae. This caused a marked improvement in catfish flavor quality. Co-stocking ponds with threadfin shad appear to be an effective tool to reduce off-flavor incidence in channel catfish production ponds.
Split-pond aquaculture system. A split-pond aquaculture system has been developed that potentially can increase channel catfish production by 2 or 3 times that achieved in traditional earthen ponds. The new system splits an existing earthern pond into two unequal sections with an earthen levee and then links the two systems by circulating water that is pumped with a large, efficient, slow-turning paddlewheel. Fish are held in the small section and the larger section provides waste treatment and oxygen production. The new, full-size (4.5-acre) system studied by ARS scientists at the National Warmwater Aquaculture Center, Stoneville, MS, produced 77,000 pounds of fish (17,000 pouynds/acre) at a feed conversion ratio of 1.8. Based on these results, several hundred acres of split-ponds have been built by commercial farmers in Mississippi and Arkansas.
Alternative feeding ingredients. Prices of soybean meal and corn, the two most commonly used traditional feed ingredients in channel catfish diets, have increased dramatically in recent years. Using less-expensive alternative feed ingredients to partially replace soybean meal and corn will reduce feed cost. ARS scientists at the National Warmwater Aquaculture Center, Stoneville, MS, investigated the use of corn gluten feed and cottonseed meal, two promising alternative feedstuffs, as replacements for soybean meal and corn in diets for pond-raised channel catfish. The study showed that a maximum of 50% of the soybean meal in channel catfish diets may be replaced (soybean meal was reduced from 51.4% to 25.7%) by a combination of corn gluten feed and cottonseed meal (up to 20% of each in the diet) without markedly affecting the physical quality of feed pellets, fish growth, processed yield, and body composition. Results are bing used by catfish feed mills to reduce feed costs while providing a nutritionally complete feed for commercial catfish farming.
Mischke, C.C., Griffin, M.J. 2011. Mass culture of Dero digitata in the laboratory. North American Journal of Aquaculture. 73:13-16.
Robinson, E.H., Li, M.H. 2010. Channel catfish Ictalurus punctatus size and feed conversion ratio. Journal of the World Aquaculture Society. 41:829-833.
Li, M.H., Robinson, E.H., Bosworth, B.G., Oberle, D.F., Lucas, P.M. 2010. Effects of varying dietary compositions using common feed ingredients on growth and feed efficiency of pond raised channel catfish. Aquaculture Research. 41:1133-1139.