Microbiological aspects of fish cultured in wastewaters - the South African experience

Health risks associated with the utilization of wastewater for fish production were studied by investigating the possible incorporation of pathogenic microorganisms into fillets of fish. Fish were cultured in cages in stabilization ponds at two municipal wastewater treatment facilities, and in a flow through and recirculating system receiving humus tank effluent. Water and fish were analysed for total and faecal coliforms, Salmonella and coliphages. Even though high numbers of faecal coliforms and coliphages were detected in the wastewater and in some instances Salmonella were isolated, none of these microorganisms were found in fish fillet. Results of this study indicate that fillets of fish grown in such wastewater pond systems are microbiologically safe for human consumption, provided that simple precautions are maintained in food handling and processing, and that ponds are restricted to domestic wastes.