The southern Chinese city of Liuzhou is on alert for piranhas after two people were attacked by the aggressive, flesh-shearing fish.

The local government is asking people to hunt the South American species and is offering a 1,000 yuan ($160) reward for every fish caught, dead or alive.

"Fishing with nets is not allowed in the section of the river that flows through the city, but we have made an exemption," official Wei Yongwen told the China Daily.

"Five fishing boats with experienced fishermen have been deployed on the river since Monday.

"In addition, more than 40 other fishermen from the local fishing association have joined us as well. They all use small pieces of pork as bait."

The China Daily report said other people have taken up position along the Liujiang River's banks, armed with rods.

"It's horrible to know that the river has such fish. I will not swim there anymore," resident Liu Junjie told the state-run paper.

"I'll pray they catch them soon."

Two people have been badly bitten this month by the aggressive fish.

Zhang Kaibo, 31, was attacked as he washed his dog in the Liujiang River, acording to Hong Kong Cable News.

The fish latched onto the man's hand, leaving deep lacerations.

He shook the fish loose and took it home, where he kept it alive. A friend was then bitten when he tried to handle the sharp-toothed omnivore.

"I thought it was a pomfret fish, but when I saw the teeth, I realised it was a piranha," he told Cable News.

While locals are hunting the fish, the piranhas' days may be numbered anyway.

Piranhas die when the water temperature drops below 15 degrees Celsius, as it will do in the region over the winter.

It is not known how the South American species found their way to China.

Chinese media has said the piranhas may have been released by people who had bought them as ornamental fish and that authorities are now stepping up patrols of markets to ensure no more are sold.

Reuters/AFP