Summary

The freshwater fish silver perch (Bidyanus bidyanus) is an excellent species for aquaculture, and research by NSW Fisheries underpins an industry with the potential to become one of Australia's largest fisheries. It is currently the 3rd most valuable aquaculture industry in NSW. Silver perch aquaculture provides opportunities for the integration of aquaculture and agriculture, and the species also has potential for culture in the inland, saline areas of the state.

Feeding is one of the most important activities in aquaculture, and the efficient delivery of feed to fish is essential for successful and economic production. Although practical, least-cost diets for silver perch are available, an overall feeding strategy had not been developed. Currently many silver perch farmers attempt to feed to satiation by observing the feeding activity of the fish at or near the surface of the water. However, satiation can be very difficult to determine in characteristically turbid silver perch ponds, where not all fish feed at the surface. Feeding behaviour and activity of silver perch vary with many factors and so farmers often over-feed or under-feed their fish. Over-feeding wastes feed and adversely affects water quality, while under-feeding results in reduced growth and greater size variation; both can lead to increased susceptibility to disease. Poor feeding practices invariably increase the cost of production.

A 2-year research project was undertaken at the NSW Fisheries' Grafton Aquaculture Centre to develop a feeding strategy for silver perch. The project included a series of eight experiments which determined optimum feeding rates and frequencies for both fingerling and large silver perch over a wide range of water temperatures. The research has led to the formulation of a comprehensive feeding strategy for silver perch. This extension article, which includes some background information and instructive feeding tables, will enable rapid transfer of the new technology to industry. Adoption of the strategy by farmers will significantly improve feeding practices and lead to increases in efficiency and profitability on individual farms and across the industry.