"Third Water" Prawn Farming Project to Kick Off in Cambodia

Okayama, May 14 (Jiji Press)--An onshore prawn farming project using water known as "third water" developed by Toshimasa Yamamoto, associate professor at Okayama University of Science, will start in August in a mountain village in Cambodia. Aquaculture on land is expected to improve nutrition and alleviate poverty, but disease has been a huge hurdle so far. However, Yamamoto's third water prevents disease-causing agents from spreading. "It is magic water that enables aquafarming without chemicals. We can turn a mountain village into a fishing village," he says. The water is made by mixing each liter of freshwater with some 10 grams of such minerals as sodium, potassium and calcium. The salt level in the water is almost the same as that of fish and shellfish. It tastes slightly salty. The water, which costs one-10th or less of the price of artificial seawater, was granted a patent in 2012. To date, tiger puffers and eels have been cultivated with the water. Fish do not get sick because third water has features that do not exist in nature and does not contain the disease agents often found in seawater and freshwater. Fish grow faster than in their natural state. This is believed to be because they do not have to use energy to adjust osmotic pressure. Such adjustment is necessary when they live in seawater or freshwater. The university ships tiger puffers six to eight months earlier than those cultivated in seawater. The project in the Cambodian province of Takeo will be led by the Japan International Cooperation Agency. Some 30,000 giant river prawns will be reared at each of three farms. The prawn sells for eight times the price of ordinary fish in the Southeast Asian country. JICA will verify the effects of using the water on the efficiency and cost reduction. The water is likely to play a role in promoting onshore aquaculture technology in developing countries, says Kenji Kaneko of JICA's Rural Development Department. It is necessary to shift from ocean-based aquafarms, which are affected by weather, Yamamoto says. Water temperature adjustment is mostly unnecessary at land-based aquafarms in Cambodia as temperatures remain high throughout the year. However, electricity is needed to control water temperatures in some areas and with certain kinds of fish. Yamamoto is also studying a way to cut power generation costs by using geothermal and solar heat. "Aquaculture is possible anywhere with only water and electricity. In the future, we hope to conduct aquaculture in deserts and even space." END