The sturgeon which measures 1.3 meters and weighs about 13.5 kilograms (29.8 pounds) is the largest Chinese sturgeon ever discovered in the lake, the fishery bureau of the Poyang County said.
Mao Qilong caught the sturgeon and reported it to the bureau on Sunday, state-run Xinhua news agency reported.
It was then released to the lake on the same day, the bureau said.
Believed to have lived at the same time as dinosaurs, the Chinese sturgeon, has existed for more than 140 million years.