The Ministry of Agriculture issued a document yesterday urging the destruction of all of the species and strict implementation by related groups.

It comes after last Wednesday's notice from the Beijing Muinicipal Agricultural Administration that banned the fish, whether they were in commercial aquaria, pet markets or households.

The ministry's document appealed to administrative departments at all levels nationwide to co-operate with the local industrial and commercial administration sectors to remove any of the species being sold and crack down on people illegally introducing, producing and dealing in the non-indigenous aquatic species.

The first notice caused outrage from several aquaria, until an agreement was reached with the agricultural administration.

According to Huang Lichun, a senior engineer and head of the Beijing municipal fishing industry supervision and administrative station, his phone became a hot line the day the ban was issued.

It is believed some of the fish have been let loose in the Yellow River, prompting the urgent notice.

But experts said there is no need to worry as the species cannot survive in northern China's climate.

Beijing Aquarium, which had the largest amount of the species, about 300, killed them yesterday by using a humane method.

They were placed in a special container with sodium hypochlorite, causing them to lose consciousness after up to about 30 minutes.

The dead fish will become samples to show visitors. Hu Weiyong, general manager of the aquarium, said hundreds of thousands of yuan was spent on killing the fish. Introduced in 1998, they cost up to 500 yuan (US$60) to breed.

Each was sterilized by the time it was 18 months old, when the fish becomes sexually mature.

Fisheries experts have called on detailed and specific laws in relation to foreign species being introduced to China.

(China Daily December 26, 2002)