It will be the first time that researchers in Shanghai have used fish to monitor the environment, said Tang Wenqiao, a biology professor with Shanghai Fisheries University at the China Fishery Conference on Tuesday.

Mullet, also known as "Asian mermaids," are fish whose biological index changes if the heavy metal or poisonous organic content of water is too high. Mullet is deemed as natural monitor of water quality, said Tang.

Suzhou River, Shanghai's mother river, was badly polluted in the 1970s. People can seldom find fish and shrimp from the river for 27 years, according to Liberation Daily, a local newspaper.

Over the past decade, the government has invested 11 billion yuan (US$1.38 billion) in improving the water quality.

A simulated experiment in the river proved that the mullet can now live in the current water environment, said Tang.

(Xinhua News Agency October 19, 2006)