[3][5] Chinese water dragons are large diurnal lizards adapted for dense subtropical forests replete with unpolluted streams.

Arthropods are their main source of food, though worms, snails, vertebrates, and plants make up a notable portion of the diet as well.

One amphibolurine, the Australian water dragon (Intellagama lesuerii) is so anatomically and ecologically similar to Physignathus cocincinus that it was once (erroneously) placed in the same genus.

Their meat is in high demand in Vietnam, and captive breeding is currently incapable of replacing wild collection by hunters and poachers.

Habitat loss is another source of pressure, as undisturbed streamside forest is converted into cropland or subjected to illegal logging and other human activities.

[10] According to most genetic analyses, Physignathus cocincinus is the sister taxon or the most basal (earliest branching) species of the agamid subfamily Amphibolurinae.

Adult Chinese water dragons are large and robust lizards; males can grow up to 90 cm (3 feet) in total length, including the tail.

[5][3]Chinese water dragons show distinct sexual dimorphism; the males are heavier (up to 0.6 kg or 1.3 lbs) and have prominent display features.

[5][3] Chinese water dragons are native to the subtropical forests of southern China (Guangdong, Guangxi, and Yunnan provinces) and Southeast Asia (Vietnam, Laos, portions of Cambodia, eastern Thailand).

Their reliance on undisturbed forest streams indicates that, despite their wide extent of occurrence in southeast Asia, Chinese water dragons are a geographically restricted species.

If threatened, a Chinese water dragon will leap or run to the nearest stream and either swim to safety or remain submerged for up to 90 minutes.

Movement and range patterns appear to be similar between the hot and wet summer and the relatively cool and dry winter, unlike most other subtropical reptiles.

This may be an unintentional artefact of the fact that Hong Kong's dry season during the study interval (2015–2016) was unusually warm and wet.

Termites, ants, orthopterans (grasshoppers and crickets), earthworms, and spiders all make up a significant portion of the diet, along with insect larvae, snails, and various other prey items.

[7][21] A female housed at the Smithsonian National Zoo produced viable offspring in 2016 and 2018, along with numerous unfertilized and nonviable eggs.

Physignathus cocincinus is the only agamid known to reproduce via parthenogenesis, though the low hatch rate suggests that this is an accidental occurrence rather than an ingrained evolutionary strategy.

[7] Though locally abundant in some areas, the Chinese water dragon faces persistent unrestrained threats and a steadily declining wild population.

[2] In accordance with a 2022 proposal,[5] the Chinese water dragon has been listed on CITES Appendix II (requiring a CITES-approved permit for export) since 2023.

[2] A 2017 population survey in Thua Thien Hue Province, Vietnam estimated that up to 250 individuals in total were present at the 11 sampled sites (combined).

This is far below the several thousand expected to sustain long-term genetic diversity for a species restrained to narrow riparian habitats.

[6][2][20][5] According to a series of 2016 interviews with 21 rural hunter groups, water dragons are a frequent and easy target of traps and hand collecting throughout Thua Thien Hue.

Water dragon meat is typically sold to local restaurants, while eggs are stored in rice wine to be used as traditional medicine.

[2] Wild water dragons are captured and sold as pets on social media platforms for both Vietnamese customers and the international markets of Europe and the United States.

[2][5] In Thua Thien Hue, illegal logging and a major highway construction project are likely partially responsible for losses in the Nam Dong and A Luoi districts.

Coal mining, stream pollution, and climate change may also threaten the species, as reported for ecologically similar reptiles in the region, such as the Chinese crocodile lizard (Shinisaurus crocodilurus).

[20][5] Despite its common name, the Chinese water dragon is exceedingly rare in China, where it is threatened by dam construction on top of the same pressures as the Vietnamese populations.