Rowland SJ, Landos M, Callinan RB, Allan GL, Read P, Mifsud C, Nixon M, Boyd P and Tully  P (2007) Development of a Health Management Strategy of the Silver Perch Aquaculture Industry. Final Report to the Fisheries Research and Development Corporation for Projects 2000/067 and 2004/089. NSW Department of Primary Industries, Fisheries Final Report Series No. 93. NSW Department of Primary Industries, Cronulla.

Summary

The native freshwater fish silver perch (Bidyanus bidyanus) is an excellent species for aquaculture, and R&D by the NSW Department of Primary Industries provides a technical basis for industry development. An industry based on pond culture currently produces around 500 tonnes annually; however, to date it has not realised its potential. In the late 1990s, there were reports of disease problems causing significant losses on some commercial silver perch farms, including regular outbreaks of a fungal disease during winter. A project to address disease and health management issues commenced in 2001 and involved monitoring fish health at the Grafton Aquaculture Centre and on selected commercial silver perch farms in coastal and western regions of NSW.

Key diseases of silver perch were identified and their incidence determined. Parasitic diseases accounted for around 80% of all records. Ichthyophthiriosis and chilodonellosis are acute diseases that can cause high mortalities if not diagnosed and treated promptly. The incidence of bacterial diseases was very low (< 3%) and there were no viral diseases. Silver perch are susceptible to two fungal diseases, winter saprolegniosis (also called winter sap or winter disease) and epizootic ulcerative syndrome (EUS or redspot). A series of experiments evaluated the efficiency, depletion and residues of some potential chemical therapeutants, and data were used in applications for minor use permits. To aid on-farm disease diagnosis and health management, a diagnostic manual and a health management plan were published. The manual is an easy-to-use, desk-top publication that will facilitate accurate and rapid diagnosis of silver perch diseases. The health management plan provides guidelines for the monitoring, treatment and prevention of diseases, as well as for site selection, design, operation and management of farms, and fish husbandry. In addition, a Hatchery Quality Assurance Program was developed to address concerns about diseases, as well as genetics and trash fish in the native fish hatchery industry. Further components of a health management strategy include extension of technology and a disease diagnostic service that is available at Government veterinary laboratories. The health management strategy should significantly improve health management and lead to increased survival, production and economic viability of silver perch farms. These improvements will facilitate further growth of the industry. The publications and strategy have application to other species and industries in Australia and overseas.