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Antibacterial Coating Improves Fish Yield at Commercial Fish Farms

JAPAN - The Fuji Trout Hatchery at the Shizuoka Prefectural Research Institute of Fishery and Kobe Steel, Ltd. have tested an antibacterial coating that improves the sanitation of fish hatchery equipment to control parasitic water mold under commercial conditions.

At fish farms, parasitic water mold is a problem because it inhibits the hatching of fish in the salmon family. The antibacterial coating is being used at a commercial fish farm in Yamanashi Prefecture and several others in Shizuoka Prefecture. Since autumn last year, fish from these farms have been shipped to market.

Using the antibacterial coating called KENIFINE, developed by Kobe Steel, it is now possible to reduce the amount of expensive veterinary medical products used so far to maintain the sanitation of hatchery equipment at fisheries and control parasitic water mold. KENIFINE offers a relatively inexpensive alternative.

For many years, a fungal removal agent called malachite green was commonly used to control parasitic water mold on fish eggs. However, a revision in Japan's Pharmaceutical Affairs Law banned the use of this substance in August 2005. To find an alternative, the Fuji Trout Hatchery and Kobe Steel in 2004 began conducting joint research and trials. Since August 2005, a veterinary medical product called Pyceze has been used to disinfect fish eggs. However, growing consumer interest in food safety is creating demand from fisheries to find a low-cost method, while avoiding chemical agents to whatever degree possible. This led to the use of the KENIFINE antibacterial coating.

After two and a half years of trials at fish farms in Shizuoka Prefecture, the KENIFINE coating was found to be effective. KENIFINE inhibits the growth of bacteria and controls the growth of fungal threads. KENIFINE is also safe. The eying rate and hatching rate of fish eggs are good, and adult fish suffer no harmful effects from the coating. In addition, KENIFINE works as a disinfectant when plated to surfaces, with similar effectiveness as Isodine for aquaculture use and antiseptic soap. With these verifications, guidelines and application manuals were completed.

Kobe Steel Group company Shinko Wire Company, Ltd. and its subsidiary Shinko Wire Stainless Co., Ltd. are producing stainless steel wire plated with KENIFINE for use in hatching nets. Until now, nets have been plated after being woven. However, film formation at the points where the steel wires cross is difficult and becomes a breeding ground for bacteria. Plating the wire first before making the nets solves this problem.

Kobe Steel aims to introduce the KENIFINE coating throughout Japan in a wide range of fields to contribute to fish farms and food safety. It also aims to conduct studies in applying the coating to salt-water applications.