"The 3.6-meter, 250 kilogram fish, the largest of its kind seen in the last six years, was caught in the Yangtze River in Jiayu county on Monday morning," said Ma Daoyun, an official with Xinluo-based national white-flag dolphin nature reserve.

After receiving reports from local villagers, a team from the reserve tried to get the fish back to deep water but it died on Wednesday night.

The fish had six hooks in it, according to the rescue team.

Local authorities are tracking down the fishermen who fled the scene.

"The case is rare because the fishermen continued trying to pull the fish from the water even after villagers warned them that the species was under top state protection," said Xiong Yuanhui, a senior engineer of the reserve.

"Most fishermen would report to the reserve if they accidentally caught rare fish," he said.

The endangered Chinese paddlefish has been dubbed "the giant panda of the rivers" as it too lives only in China.

A scientific research team organized by the Chinese government in 2002 searched for traces of paddlefish along the Yangtze River but found no evidence of its existence in the wild.

Scientists still do not know how many of the species survive in their major habitat - the Yangtze River and the Qiantang River in eastern China.