About 20 beautiful and expensive arowana fish will go on display as part of Hanoi 's millennial anniversary next week.

The species, which the World Conservation Union says are at high risk of extinction, have become popular as pets in Vietnam during the past five years with thousands now in private aquariums, especially in Hanoi and HCM City .

Most are raised in Vietnam and originate in Singapore , Malaysia , Indonesia and China .

Some cost up to 15,000 USD.

The average price for an 18cm-long fish was about 1,000 USD, said a Hanoi Bonsai and Pets Association member, Manh Hoang.

"The fish is expensive because it is valuable in terms of feng-shui," he said. "Asians consider it a symbol of power and wealth. The fish can bring good luck to the owner."

Another member of the association explained that the fish needed five to six years to mature and can reach a length of 60-70cm.

It lives for up to 50 years.

"The longer the fish live the more beautiful its colour and the more expensive it becomes," he said.

There are four common type of Asian arowana in Vietnam : The red-tail golden; the cross-back golden; the red, and the green.

The fish will be on display at the Hanoi Museum in Pham Hung Street from October 5-10./.