East China's Anhui Province has resorted to the biological measure of using algae-eating fish to clear the polluted Chaohu Lake, the country's fifth largest body of freshwater.

This week, Chaohu Fishery Administration put more than 50,000 silver carp fry into the lake. It will add another 1.55 million in the coming 20 days, said deputy director Wu Changjun on Wednesday.

A silver carp will have eaten between 40 and 50 kilograms of blue algae when it reaches one kilogram. The school of fish is expected to effectively curb the blue algae pollution.

The fish could also sell for 7.5 million yuan (US$1.05 million) on the market by year end, 15 times the investment in the fry. While the fishery authority has paid for the fry, fishermen are free to catch the mature fish, according to Wu.

From June to August last year, the nutrient runoffs and other pollutants caused blue-green algaes to bloom in the country's Taihu, Chaohu and Dianchi lakes, endangered water supply in nearby cities and posed great threat to aquatic life.

Blue-green algae has caused water pollution in the lakes where whitebait production is declining.

The output of whitebait, a small sprat famous for its fresh and tender meat, has dropped by 500 tons, 20 percent lower than last year's fishing season compared with the year previous.

An algae outbreak in the eastern Taihu Lake, the country's third largest freshwater lake, provided an alert at the end of Mayas it rendered tap water undrinkable for about 10 days for more than one million residents in Wuxi, Jiangsu Province.

(Xinhua News Agency February 21, 2008)