Checkered Keelback

草花蛇 (cao3hua1she2)

Status: Not Protected




X. piscator in a lotus pond

X. piscator playing dead

Young X. piscator eating a fish



X. piscator in the wild

Catching X. piscator in a paddy field



Family Colubridae, subfamily Natricinae


Max. length 120 cm


Occurrence in Taiwan

Throughout Taiwan and Kinmen, up to 500 m altitude. (Distribution map)


Global Distribution

Afghanistan, Pakistan, Sri Lanka, India (Maharashtra, Arunachal Pradesh), Burma, Thailand, Laos, Vietnam, West Malaysia, Indonesia (Sumatra, Java, Borneo, Sulawesi), C/South China (Zhejiang, Jiangxi, Jiangsu, Fujian, Guangdong, Guangxi, Hainan, Yunnan, Guizhou, Anhui, Hunan, Hubei, Shaanxi), Taiwan.




This snake is medium in size; total length up to 120 cm. There are 17-19 (19 at mid-body) rows of scales, all keeled except those on the flanks. Head is oval to slightly triangular; body is moderately stout and round; tail is long. Eye is medium-sized; iris is dark gray to gray black, heavy but uniform deposit of black pigment interpersed with dirty yellow, and pupil is round, jet black, surrounded by broad ring of bright to dirty yellow. Tongue is dark gray to black, fork tips darker than stem. This snake is characterized by great diversity in coloration. Upper head is olive gray except for frequently indistinct pattern of black near mid-line and posterior end of parietals. There are two posteriorly directed oblique and parallel black lines near eye, the anterior line extends from lower edge of eye to mouth while the poserior line from a point back of eye to corner of mouth; the latter may join with a black line forming a broad ''V'' or ''W'' on the nape. Usually, upper body is olive-brown to reddish with black spots arranged in alternating rows, creating a checkered appearance, which is more distinct anteriorly. Ventral head and neck are dirty white to cream, may be tinted with yellow or red. Ventral body bears horizontal bands due to black pigmentation along anterior margin of the ventral; the horizontal lines are more prominent in mid and posterior part of body. Anal scale is divided and subcaudals are paired, with pigmented borders.


Biology & Ecology

This diurnal or nocturnal snake is one of the most common serpents on Taiwan. It is semi-aquatic and seldom ventures beyond the close vicinity of water, inhabiting ponds, streams, flooded rice fields, and other freshwater bodies. Its prey includes fish, frogs, toads, tadpoles, insects, lizards, birds, mice, and even small snakes. X. piscator usually stalks its prey and grasps it with its vice-like jaws and if in a favourable position, begins to swallow it immediately. Often frogs will croak for a considerable amount of time from within this snake's stomach before succumbing to its digestive fluids or suffocation.

A very active snake by day but it may hunt frogs by night. The snake may be aggressive and is usually moderately nervous when first confronted in its habitat; it will usually strike and bite if disturbedand when it senses that it cannot escape its challenger. If chased over long distances it may jump clear off the ground repeatedly in order to escape.

The snake is a prolific breeder: clutches containing 8-88 eggs (usually more than 30) of 1.3-2.4 x 1-1.5 cm have been recorded. Hatchlings measure 17-19 cm in total length. Females who mate in spring and fall, respectively, lay eggs in late spring-summer and the following spring. The male often continues to exist with the female throughout the mating season.

Colorations vary, some consisting of dark spots arranged in a quincunx-like pattern often separated by a whitish network. It is often olive-brown or olive-green dorsally and pale brown or white underneath. Often the dorsal coloration is accompanied by lighter spots arranged in a checkered pattern (hence the English common name).

While X. piscator does not possess any venom glands, its saliva might contain toxic elements: it has been reported numerous times that after a bite the wound tends to swell and itch severely.



Xenochrophis stems from the Greek words xenos = strange, ochros = pale yellow, and ophis = snake.

piscator is Latin for "fisherman, angler", alluding to its piscivorous habits

The Chinese name 草花蛇 (cao3hua1she2) means "grass flower snake".






Reptile Database


On the taxonomy of the Xenochrophis piscator complex (PDF file)



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