Lu Wei, is the general manager of River Red crayfish

The crustacean is omnivorous and aquatic, and has relatively low mobility. They are active mostly within a small area and live in small caves on sloping banks where they dig holes as deep as 50 cm, to "get married".

Besides farmed crustaceans, there are also crayfish that are caught from lakes and rivers in Xuyi. In other parts of the country, crayfish are raised in rivers and lakes.

Liu says farmed crayfish have a clean and shiny belly. Crayfish is best prepared when very fresh, and one indication of freshness is when their tails are tightly curled up. Those with roe are always in great demand.

Dong Keping, Beijing-based gourmet, says the crayfish was introduced to Japan by Americans, then brought to China by the Japanese in 1929.

"It was used to feed bullfrogs, which the Japanese ate," he says.

In China, crayfish farming didn't start until in the 1990s although it has now become a culinary favorite in Hunan, Hubei, Jiangxi, Anhui and Jiangsu provinces.

Crayfish are best from May to October, but farmers in Xuyi have learned to coax them into production all year round, with the building of special greenhouses over ponds in the cooler seasons.

Xuyi is currently China's biggest distribution center for crayfish and it expects its farms to up production to 10 billion yuan a year, and increase to 20,000 hectares over the next three years.