Photo/Illutration Towa Suisan, an aquaculture company in Saiki, Oita Prefecture, uses about 75 LED lights in five tanks. Photo taken June 22 (Jin Nishioka)

SAIKI, Oita prefecture--A “light farming” technique that stimulates the growth of flatfish varieties is taking hold in Oita Prefecture, one of the nation’s top producers of farmed flounder.

Researchers found that raising flounder for 12 hours a day under green LED lights significantly speeds up growth and shortens the time until the fish are ready for shipment to markets.

Towa Suisan, an aquaculture company in Saiki, uses about 75 LED lights in five tanks.

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Towa Suisan, an aquaculture company in Saiki, Oita Prefecture, uses about 75 LED lights in five tanks. Photo taken June 22 (Jin Nishioka)

Normally, it takes about one year and two months to raise fry to adult size weighing around 1 kilogram, but 12 hours of light during the daytime can shorten the time by three months or so.

The prefectural government is pushing for the widespread introduction of the LED technique to improve the efficiency of flatfish farming.

Akiyoshi Takahashi, a professor at Kitasato University’s School of Marine Biosciences, where he specializes in fish endocrinology, is behind the latest research.

“We do not know the precise mechanism,” said Takahashi, 65.

However, he believes the green light activates brain functions related to the appetite and behavior of flatfish, which in turn increases the amount of food they consume.

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