Preliminary dipping of Hasa-hasa (Rastrelliger brachysomus, Bleeker) in a solution containing 50 parts per million of Biostat for 15 minutes ft-as effective in prolonging the freshness of fish for 16 days. The fish preserved in Biostat ice alone were good for 11 days while those treated with ordinary ice lasted for 7 days. The fish used in this experiment were purchased from a local market center and the fish were not in a rery fresh state. Effectiveness of Biostat in prolonging the freshness of fish can be accurately determined if the experiment is conducted on fish caught right in the fishing grounds.