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Kobe Steel Introduces Antibacterial Coating for Fisheries

The Fuji Trout Hatchery at the Shizuoka Prefectural Fisheries Experiment Station has been conducting research on decreasing the occurrence of parasitic water mold, which affects the yield of fertilized eggs of rainbow trout and other fish in the salmon family. The study found that Kobe Steel's antibacterial coating, Kenifine, was effective at reducing parasitic water mold.

Fish hatcheries throughout Japan have been grappling with outbreaks of parasitic water mold, which inhibit the incubation rate of fertilized eggs. Malachite green, a type of dye, has been highly effective at controlling water mold in fish. Since the 1950s, malachite green had been used as a general countermeasure against water mold.

However, since the mid-1970s, malachite green has been suspected of being a carcinogen. In 1981, the United States prohibited the use of the substance in food-related applications. The EU and Norway placed a similar ban in 2002. In July 2003, Japan revised its Pharmaceutical Affairs Law, which curtailed the use of malachite green in egg incubation facilities and fish farms. An extension until July 2005 allows the use of the chemical on eggs raised at seedling production facilities on land and young fish of 1 gram or less.

Companies have been investigating alternatives to malachite green. New chemical agents have gained approval and are anticipated to go on the market in the near future. Regional and consumer interest continues to support discontinuing the use of chemicals in fish farming, or if used at all, to minimize the amount.

At the Fuji Trout Fishery, researchers verified that Kenifine was not only effective in reducing water mold on fertilized eggs, but it had no adverse effects on the eggs. Owing to these benefits, the Shizuoka Prefectural Fisheries Experiment Station and Kobe Steel believe that the Kenifine coating will draw increasing attention from fisheries across the country.


Kenifine is an electrolytic plating that contains nickel and trace amounts of other elements. When plated to the substrate, the ions in the Kenifine coating yield antibacterial properties. It has demonstrated that it is effective at controlling microorganisms in comparison to conventional surface-treated products, such as antibacterial paint and antibacterial stainless steel. Highly resistant to corrosion in fresh water, the alloy coating also has outstanding antifungal and antialgal properties. Kenifine has also passed various safety tests, including acute toxicity tests, set by the Society of Industrial-Technology for Antimicrobial Articles (SIAA).

Following development in 2001, Kobe Steel has licensed the Kenifine technology to six companies and five other firms are using it on a trial basis. Improvements to Kenifine have made it resistant to discoloration. In addition to metals, the coating is also available in powder form for use on plastic surfaces.

Most recently, laboratory testing conducted at Iwate University found Kenifine was effective in reducing the growth of mouse hepatitis virus (MHV, or mouse coronavirus), which is a close relative of the SARS (severe acute respiratory syndrome) coronavirus (CoV). Both MHV and SARS CoV are in the same group of coronaviruses.