Description: A large terrapin, averaging 12-20 cm in carapace length, but recorded at a maximum of 29 cm. Carapace olive-green, with 2-3 irregular yellow stripes extending from eye to side of neck. A bright red patch behind each eye; orange-yellow in some specimens. In old individuals may be faded or entirely absent. Old males develop dark-coloured head and are less brightly coloured. Plastron yellow, with an irregular series of yellowish marks heavily bordered in black. Legs olive-green, with several yellow stripes extending down to the claws. Feet prominently clawed and webbed. Tail short. Young individuals similar to adults, but with brighter green carapace, and swirl markings much less evident. Lower sides of carapace yellow. A black spot on each scute in hatchlings.
Habits and habitat: A terrapin of quiet waters in sunny portions of swamps, ponds and reservoirs. Usually seen basking on banks. Occasionally found in slow-flowing streams. Since its establishment in Hong Kong (about 1980), the native Chinemys reevesii has become much less common, possibly indicating that the two species compete for food.
Diet: Feeds on aquatic vegetation, frogs, and small fish; occasionally on carrion.
Reproduction: Hatchlings range from 2.5 to 3 cm in carapace length.
Distribution: Its normal range is North America, but has been introduced in Hong Kong and elsewhere in the world as an indirect result of the pet trade. In Hong Kong is well established in several reservoirs such as Tai Tam, Wong Nai Chung, Aberdeen, Shing Mun, Pokfulam and the Kowloon Reservoirs group. Also occurs in fish ponds in Inner Deep Bay.
Diagnostic features: Carapace and head olive-green, with yellowish stipples; a bright red to orange-yellow patch behind the eye; legs with yellow stripes.