The Liuzhou city government has also declared the river off-limits to swimmers while the hunt goes on for the flesh-shearing fish, believed to have been illegally imported for exotic aquariums, according to the China Daily.

"It's horrible to know the river has such fish. I will not swim there anymore... I'll pray they catch them soon," the paper quoted local resident Liu Junjie as saying.

The city government announced the bounty and other incentives to catch the fish on Tuesday after a piranha bit a man who was washing his dog in the Liujiang river.

The man caught the fish, allowing it to be identified, and said he saw two others in the river at the same time.

The "dead or alive" bounty is worth 1,000 yuan ($157), which is a big sum for local fishermen and reportedly prompted many to line the banks of the river with their rods.

"Some of my friends went fishing on Tuesday. Just think, the money they get from three piranhas equals their monthly income. How can they resist it," Liuzhou resident Zhu Feijie said, according to the China Daily.

Authorities have also given out free pork and other meat for the fishermen to use as bait, while a ban on using fishing nets in parts of the river that flow through the city has been temporarily lifted, the paper said.

However no piranhas have yet been caught in the hunt.

Importing piranhas for exotic aquariums is banned in China and other Asian countries due to fears the fish will enter local waterways and breed rapidly without predators.

Police in the Philippines arrested five people for selling piranhas in December last year.