World aquaculture production is dominated by omnivorous fish species that live in freshwater, including various carp and catfish species. Soybean meal is a prominent ingredient used in prepared diets for these species, often constituting 50 to 60% of the total formulation. Such levels of incorporation are possible due to adequate palatability of soybean meal and its excellent nutritional value for these species, including high levels of crude protein, complementary amino acid profile and relatively high nutrient digestibility. For many omnivorous freshwater species cultured throughout the world, soybean meal has largely replaced more costly protein feedstuffs in diet formulations, such as fish meal, while maintaining optimal fish production. As a result, the cost of fish production has been reduced substantially. While aquacultural production continues to expand worldwide to meet the growing demand for seafood, the use of soybean products will play an even more important role in providing high-quality protein for various fish species.
A feeding trial was conducted in Harbin, Heilongjiang Province, located at 46o north latitude, to demonstrate fry to fingerling growth performance of mirror carp using the ASA 80:20 pond production model and soymeal-based fry and fingerling feeds. Fish were stocked in two ponds of size 6.0-mu and 7.8-mu, respectively, at a density of 3,000 mirror carp and 1,000 silver carp fry per mu, and in one pond of size 6.5-mu at an estimated density of 4,600 mirror carp and 1,000 silver carp fry per mu. Mirror carp stocked at 3,000/mu grew from 0.6g to an average weight of 165 g per fish in 85 days of feeding. Gross production averaged 406 kg/mu for mirror carp and 94 kg/mu for silver carp. Average survival rates for mirror carp and silver carp were 82% and 75%, respectively. Mirror carp FCR with the soymeal-based feeds averaged 1.24:1. Average net economic return was RMB 1,305 per mu, for an average return on investment (ROI) of 53.3%. Mirror carp stocked at the estimated density of 4,600/mu grew from 0.6 g to 96 g in 85 days, with an FCR of 1.26:1 and an ROI of 48.6%. Results of the feeding demonstration showed that mirror carp exhibited excellent growth performance, FCR, survival and economic return with the ASA soymeal-based feeds and 80:20 production technology. The use of extruded, floating feed significantly reduced labor costs, lowered fish FCR, avoided feed waste, improved water quality, and made it easier to observe fish feeding behavior and health.