Jin Wankun checks a fish from his fish farm.

With his legs weakened from six long decades of field research and his fingernails white from working in water, Jin Wankun has been dubbed "Grandpa Fish" by Chinese media for filling the nation's dining tables and is often compared with Yuan Longping, a Chinese agronomist known as father of hybrid rice who helped feed people around the world.

Jin Wankun works at his fish farm.

Jin was born to a poor Tianjin fishing family in 1932.

He established a successful freshwater fish farm after 1949 where he expanded his research in breeding, production and aquaculture through reading and observation day and night at the farm pond.

Jin even missed out on his children's weddings to stay monitoring the pond, afraid of missing a key moment in the breeding process.

Jin Wankun (center) holds a fish from his fish farm.

Today his fish farm produces 6 billion fish annually and is a major freshwater fish base of northern China.

Jin has cultivated more than 10 new varieties of aquatic products approved by the state and claimed more than 10 national invention patents.

Jin Wankun dissects a freshwater fish at his lab.

Jin has led more than 20 research projects, authored more than 90 papers and five special studies.

Nowadays Jin's poor health prevents him spending every day at the pond, but he still refuses to give up working entirely.

Jin Wankun inspects his fish farm in Tianjin on April 15, 2022. (Photos: Xinhua)

He observes the fish every day with the help of his colleagues and then rests on a wooden bed.

Jin says he wants to recruit young engineers who can lead the team towards molecular breeding, which uses molecular biology tools in fish breeding.

(Compiled by Yang Shi; Edited by Huang Jingjing)