Lake Taihu, which straddles Jiangsu province as well as Zhejiang province, has been severely polluted by sewage as well as industrial and agricultural waste, triggering a blue-green algae plague.
Authorities started using fish to try to clean up the lake in February last year when they released 10 million mostly green and silver carp into the water, after the algae tainted the drinking supply of millions of residents.
Over the next few days, around 20 million more algae-eating fish will be released into the water, the Taihu Lake Fisheries Management Committee said in a statement Monday.



