With records of specimens over three metres (ten feet) and possibly 7 m (23 ft) in length, it was one of the largest species of freshwater fish.

Since the 1990s, the species was officially listed by the International Union for Conservation of Nature (IUCN) as critically endangered, and was last seen alive in 2003.

[9] The teeth were small, sharp, canine shaped and inward curling, and became proportionally smaller relative to the jaw during growth, and in mature adults were completely fused into the bone.

[11] The maximum length of the Chinese paddlefish is often quoted as 7 m (23 ft), with this estimate apparently being given by C. Ping (1931), though according to Grande and Bemis (1991), specimens over three metres (ten feet) had not been definitively measured.

[9] Ping recorded that fishermen in Nanjing caught a Chinese paddlefish with a length of 7 metres (23 ft) and a weight of 907 kilograms (2,000 lb).

The oldest paddlefish fossil is that of Protopsephurus from the Early Cretaceous of China, dating to around 120 million years ago.

[19] The oldest representatives of the genus containing the American paddlefish (Polyodon) date to around 65 million years ago, from the beginning of the Paleocene.

[19] †Protopsephurus †Paleopsephurus †Psephurus †Crossopholis Polyodon The Chinese paddlefish was native to the Yangtze (Chang Jiang) River basin and its estuary at the East China Sea.

The species spent part of its life in the lower section of the Yangtze, including the brackish water of its estuary, but migrated upriver and into major tributaries to congregate for spawning, which occurred in spring, from mid-March to early April.

[9][28] Paddlefish, like other Acipenseriformes and several other groups of vertebrates, engage in passive electroreception (the sensing of external electric fields) using structures called ampullae that form an extension of the lateral line system of sensory organs.

The last records of Chinese paddlefish in the Yellow River basin and its estuary date back to the 1960s, although declines were realized between the 13th and 19th centuries.

[26]Since 2000, there have been only two confirmed sightings of the fish alive, both from the Yangtze basin: The first was a 3.3-metre (10 ft 10 in), 117-kilogram (258 lb) female caught at Nanjing in 2002 and the second a 3.52-metre (11 ft 7 in), 160 kg (350 lb) female accidentally caught at Yibin, Sichuan, on January 24, 2003, by fisherman Liu Longhua (刘龙华);[31] the former died despite attempts to save it and the latter was radio-tagged and released, but the tag stopped working after only 12 hours.

[1][32] During a search conducted in the Yangtze basin from 2006 to 2008, a research team from the Chinese Academy of Fisheries Science in Jingzhou failed to catch any paddlefish,[32] but two possible specimens were recorded with hydroacoustic signals.

The paddlefish was heavily overfished in all stages of growth from fry (which were easily captured by traditional fishing methods) to adult, which combined with the long generation time due to its slow maturation led to reduced sustainability of viable populations.

[30] A similar recommendation was also made by the Species Survival Commission Sturgeon Specialist Group of the IUCN in September 2019.