Striped Stream Snake (non-venomous)

Description: A small- to medium-sized water snake, with an average total length of 35-48 cm, but can reach 68 cm. Females larger than males. Back light brown or tan in colour, with three dark brown or blackish stripes particularly evident in young snakes. Old individuals dull brown on top, with faint stripes. Scales very strongly keeled, forming noticeable ridges on back and flanks. Labials and ventral scales dull-to-bright yellow, occasionally with a few brown dots. Labials sometimes flushed with pink or flesh-coloured rather than yellow. The only Hong Kong snake with 11-16 upper labials, of which the last 4-5 are often horizontally divided. Nostrils open on top of snout, typical of aquatic species.

Habits and habitat: A totally aquatic snake. Inhabits pools of moderate to swift-flowing hill and mountain streams in forested areas. In Hong Kong occurs in both large and small streams between 150 m and 825 m. Strictly nocturnal, hiding under rocks and stones in stream beds during the day. A timid, inoffensive snake, which does not attempt to bite when caught, but may defecate in self-defence like other Opisthotropis species. Shares its habitat with Platysternon megacephlaum, Leptolalax pelodytoides, Tropidophorus sinicus and Opisthotropis andersonii.

Diet: In captivity feeds on small tadpoles and fish.

Reproduction: Little is known of its breeding habits. Lays up to 6 eggs.

Distribution: First recorded from Shek Kong catchwater in 1974. Is now also known from several localities in central New Territories and on Lantau Island. Widely distributed in southern China, but apparently not in Guangdong.

Diagnostic features: Light to dark chocolate-brown dorsally; with rows of strongly keeled dorsal scales; 11-16 upper labials, the posterior ones divided horizontally.