APPENDIX D - Silver Carp Culture in Sewage Ponds
1. SUMMARY
Significant seasonal fluctuation characterizes the amount of domestic sewage water around recreational areas in the temperate zone. The summer peak overloads the purification plants and destabilizes the steady state and its normal efficiency. To purify and utilize this surplus summer domestic sewage, we have developed a domestic sewage oxidation fish pond technology.
Herbivorous fish have a paramount role in this technology, since they constitute some 90-95 percent of the stocking population as well as that of the yield. They utilize natural food not utilized by common carp and, at the same time, favourably increase the efficiency of water reclamation.
The best result was achieved at a sewage water load of 100 m3/ha/day. With 100 m3/ha/day sewage water during the culturing period, 400-600 kg nitrogen and 80-120 kg phosphorus was introduced into the pond system.
In a properly operating system, the elimination of 80-90 percent of phosphorus and nitrogen load is warranted.
With the stocking structure described, 1.8-2 t/ha net output could be achieved at a 100 m3/ha/day sewage water load.