The checkered keelback (Fowlea piscator) is a common, non-venomous water snake of ponds, lakes, streams, canals and paddy fields across India, recognised by the checkerboard pattern of dark spots on its olive-brown body and by its diet of fish and frogs. Despite being harmless to people, the checkered keelback is often feared and killed because, when disturbed, it flattens its neck and bluffs like a cobra.
This evergreen explainer covers what the checkered keelback looks like, where it lives, what it eats, why it bluffs, how it breeds, how it differs from dangerous snakes and why it should be left alone. Last updated: 22 October 2026.
| Quick Facts | Details |
|---|---|
| Common names | Checkered keelback, Asiatic water snake, fishing snake |
| Scientific name | Fowlea piscator (Schneider, 1799), formerly placed in the genus Xenochrophis |
| Family | Colubridae (subfamily Natricinae, the keelbacks and water snakes) |
| Venom status | Non-venomous to humans; at most very mildly venomous rear-fanged, with no medical significance |
| Typical adult length | About 0.8 to 1 metre; large individuals can reach about 1.5 metres |
| Habitat | Ponds, lakes, rivers, canals, marshes, rice paddies and wetlands, often near villages |
| Activity | Mainly diurnal, active in the day and early evening |
| Reproduction | Oviparous (egg-laying); large clutches, often several dozen eggs |
| Main diet | Fish, frogs, tadpoles and other small aquatic animals |
Key Takeaways
- The checkered keelback (Fowlea piscator) is a non-venomous water snake of India that is harmless to humans and has no dangerous venom.
- The checkered keelback gets its name from the rows of dark squares and spots on its olive-brown or grey body, along with strongly keeled scales that feel rough.
- The checkered keelback feeds mainly on fish, frogs and tadpoles, and it is often found hunting in paddy fields, ponds and drains.
- When threatened, the checkered keelback flattens its head and neck to imitate a cobra, hisses and strikes with a closed mouth, but this is bluffing, not a venomous attack.
- The female checkered keelback lays a large clutch of eggs near water, and the hatchlings can swim and hunt from the first days of life.
- The checkered keelback should not be killed, because it controls frog and fish populations, and a bluffing display does not make it dangerous.
What is the checkered keelback?
The checkered keelback is a medium-sized, non-venomous, semi-aquatic snake, scientifically named Fowlea piscator, that is widely found in freshwater habitats throughout India and much of South and Southeast Asia. It is also called the Asiatic water snake or the fishing snake, and it is among the most frequently encountered water snakes in the country.
The scientific name has changed over time. Older books place the snake in the genus Xenochrophis, as Xenochrophis piscator, and the name is still used in many field guides. A taxonomic revision moved the species to the genus Fowlea, so both names refer to the same animal. The species name “piscator” is Latin for “fisherman”, a reference to its fish-eating habit.
The checkered keelback belongs to the keelbacks, a group of snakes characterised by scales that have a raised ridge, or keel, along the middle. The group is part of the large family Colubridae, which contains most of the world’s harmless snake species.
What does the checkered keelback look like?
The checkered keelback looks like a medium-sized, olive-brown, grey or greenish snake with rows of dark spots forming a checkerboard pattern on the back and sides, a yellowish or whitish belly and a rough-looking body with keeled scales. Its head is distinct from the neck, and it has dark streaks behind and below the eye.
Key features that help in recognition include:
- Checkered pattern: Dark square or rounded spots are arranged in rows along the back and flanks, which creates the chessboard look that gives the snake its name.
- Dark streaks on the head: A dark line runs from the eye to the corner of the mouth, and a dark oblique mark often lies behind the eye. Some individuals also show a dark V-shaped mark on the neck.
- Eyes and nostrils high on the head: The round-pupilled eyes and nostrils are placed toward the top of the head, an adaptation that lets the snake see and breathe while most of its body is submerged.
- Keeled scales: The scales along the body have a small ridge, giving the skin a rough, matte finish unlike the smooth, shiny scales of many land snakes.
- Colour variation: The colour ranges from olive and brown to grey and even yellowish, and old individuals may look darker, with the pattern less sharp.
The average adult measures about 80 centimetres to 1 metre, with some reaching around 1.5 metres. Males are typically slimmer, while females become heavier and longer.
Where does the checkered keelback live?
The checkered keelback lives near fresh water, in ponds, lakes, rivers, canals, marshes, ditches and flooded rice fields across India, and its range extends through Pakistan, Nepal, Bangladesh, Sri Lanka and into Southeast Asia and parts of southern China. It is one of the most widespread water snakes in the Indian subcontinent.
The species is especially common in agricultural landscapes. Paddy fields, irrigation channels, village tanks and roadside drains provide a steady supply of frogs and fish, and many people see the snake while working or walking in the fields during the monsoon season. It often basks on the banks of water bodies, on rocks or on vegetation, and it slips into the water at the first sign of danger.
The snake tolerates human-modified environments better than most wild animals. It is found in the outskirts of cities, in garden ponds and sometimes in stormwater drains. In dry spells, it may move over land to find water and may shelter in burrows, under stones or in clumps of vegetation.
What does the checkered keelback eat?
The checkered keelback eats mainly fish and frogs, along with tadpoles, toads, and occasionally small crabs, insects, lizards or tiny rodents, and it hunts by both ambush and active searching in shallow water. This diet is the reason it is nicknamed the fishing snake.
The snake hunts in a few distinct ways. In shallow water, it moves its head back and forth near the bottom, startling fish and frogs. It may also lie in wait along the edge of a pond and snatch an animal that passes within range. Prey is seized in the mouth and swallowed alive, often head first. The keelback’s teeth are small and curved backwards, which prevent slippery fish and frogs from escaping.
By eating frogs and fish, the checkered keelback has a role in wetland food webs. It is itself eaten by birds such as herons, storks and kites, as well as by monitor lizards, larger snakes and mongooses.
Is the checkered keelback venomous or dangerous?
The checkered keelback is not dangerous to humans: it is harmless for practical purposes, and although it has enlarged rear teeth and a gland that produces a mild secretion, serious harm to people from this species is not recognised. It rarely bites, and a bite is usually just a minor scratch.
Most of the fear comes from appearance and behaviour. The snake is often found in the same wet places where people work, it can be quite large, and when disturbed it puts on a threatening show. Because people cannot tell it quickly from more dangerous snakes, many harmless water snakes are killed each year.
A sensible approach to any snake bite is to treat it as a medical matter. The person should stay calm, keep the bitten limb still and go to a hospital quickly, particularly if the snake is unidentified. The wound should not be cut or sucked, and no herbal or traditional remedy should be applied in place of medical care. Venomous snakes that also frequent water, such as the banded krait, can look alike to a casual observer, so waiting to see whether symptoms appear is not advisable.
Why does the checkered keelback bluff like a cobra?
The checkered keelback bluffs like a cobra because flattening its head and neck, raising the front of its body and hissing makes it look bigger and more dangerous, which can scare off predators and avoid a fight it may lose. This defensive behaviour is common among harmless snakes and is a bluff, not a sign of venom.
The snake uses several defences, usually in this order:
- Escape: Its first response is to flee, usually by diving into the water or slipping into dense vegetation.
- Hooding and hissing: If cornered, it flattens its neck sideways, rears up and hisses, which resembles a cobra’s hood.
- Mock strikes: The snake may lunge with a closed mouth, hitting the intruder with its snout.
- Musk release: When handled, it may smear a foul-smelling secretion from glands near its tail.
- Playing dead: Some individuals roll over, go limp and open their mouths as if they were dead.
These tactics have worked for the snake for a very long time. The problem is that people react to the cobra-like display with fear, and the harmless animal pays with its life. Knowing that a flattened neck alone is not proof of a cobra helps people respond more calmly.
How can you tell the checkered keelback from a dangerous snake?
The checkered keelback can be told from dangerous snakes by its checkerboard pattern, keeled scales, round pupils and its habit of staying close to water, but anyone unsure should keep a safe distance rather than try to identify a snake up close. Correct recognition depends on a combination of features, not on any single sign.
| Snake | Key features | Danger to humans |
|---|---|---|
| Checkered keelback | Olive-brown with checkerboard spots, keeled scales, dark streaks behind the eye, round pupils, found in or near water | Harmless |
| Spectacled cobra | True broad hood with a spectacle mark on the back (in many individuals), smooth glossy scales, thicker neck | Highly venomous |
| Banded krait | Bold, wide alternating black and yellow bands, a ridged back, usually active at night | Highly venomous |
| Buff striped keelback | Buff or brown with pale stripes along the body, a yellowish neck patch, also near water | Harmless in practice |
| Olive keelback | Plain olive or brownish body with a pale belly and no checkered pattern | Harmless |
The checkered pattern and the preference for water edges are strong clues for the checkered keelback, but not a guarantee. Visitors to wetlands, farmers and children should therefore avoid picking up any snake, however harmless it seems.
How does the checkered keelback breed?
The checkered keelback breeds by laying eggs, and a female typically deposits a large clutch of several dozen eggs in a hidden, moist place near water, such as under a rock, in a burrow or in rotting vegetation. The exact number depends on the age and size of the female.
Breeding usually takes place in the warmer, wetter months, with egg-laying often occurring around the monsoon, when food is plentiful. The eggs have soft, leathery shells and take about two months or so to hatch. The female does not guard the nest or care for the young after laying.
The hatchlings are small, around 15 to 20 centimetres long, and already able to swim and catch tiny prey such as tadpoles and insects. Many are eaten by fish, birds, frogs and other snakes, so only a limited number reach maturity. Large clutches are an adaptation to this high mortality.
Why is the checkered keelback important to ecosystems?
The checkered keelback is important to ecosystems because it connects aquatic and land food webs: it controls frog, fish and tadpole numbers and in turn serves as food for many birds and mammals. Wetlands with healthy snake populations tend to have well-balanced food chains.
- It regulates amphibian and small-fish numbers in ponds and paddy fields.
- It acts as prey for herons, egrets, storks, raptors, monitor lizards and mongooses.
- It serves as an indicator of wetland health, because pollution and drainage of wetlands reduce its food supply.
- It lives alongside people in farmland, where it plays a quiet role in local food chains.
Threats include wetland drainage, pesticide and fertiliser runoff that poison frogs and fish, road casualties during the monsoon, and persecution by people who confuse it with venomous species.
Should the checkered keelback be killed or protected?
The checkered keelback should be protected, not killed, because it is harmless to people, ecologically useful and a native wild animal whose killing is discouraged and may be unlawful under India’s wildlife protection framework. Many native snakes in India are protected under the Wildlife (Protection) Act, 1972, and the local forest department can clarify the legal status of any species.
If a checkered keelback is found in a courtyard, kitchen garden or home near water, the best response is practical:
- Stay calm, give the snake room and keep children and pets away.
- Do not poke, corner or hit the snake, since this increases the chance of a defensive bite.
- Contact a trained snake rescuer, wildlife NGO or forest department if the snake needs to be relocated.
- Reduce attractions around homes by clearing standing water pools, rubbish and dense weeds, and by sealing gaps.
Farmers and villagers can also benefit from learning to recognise the “Big Four” medically important snakes of India, which are the spectacled cobra, common krait, Russell’s viper and saw-scaled viper. Knowing which snakes are dangerous makes it easier to leave the harmless ones in peace.
Bottom Line
The checkered keelback is a harmless, fish-and-frog-eating water snake whose cobra-like bluff has given it an undeserved reputation. Recognising its checkered pattern and respecting it from a distance protects both people and a useful wetland animal.
Frequently Asked Questions
Is the checkered keelback poisonous or venomous?
The checkered keelback is not dangerous to humans and is regarded as non-venomous for practical purposes. It may have very mild rear-fang secretions, but these have no medical significance. Any bite from an unidentified snake should still be checked by a doctor.
Why does the checkered keelback flatten its neck?
The checkered keelback flattens its neck to imitate a cobra and scare predators. It also hisses and may strike with a closed mouth. This is a bluff, and the snake is not venomous.
What does the checkered keelback eat?
The checkered keelback eats mainly fish, frogs and tadpoles, and sometimes other small aquatic animals. It hunts in shallow water and along banks. Its Latin species name “piscator” means “fisherman”.
Where is the checkered keelback found in India?
The checkered keelback is found across India near fresh water, including ponds, lakes, canals, streams, marshes and paddy fields. It is common in farming areas and village tanks. It is also found in neighbouring countries and in Southeast Asia.
How big does the checkered keelback grow?
An adult checkered keelback usually grows to about 80 centimetres to 1 metre, and large individuals can reach roughly 1.5 metres. Females are generally larger than males. Hatchlings are only about 15 to 20 centimetres long.
What should I do if I see a checkered keelback?
Leave the checkered keelback alone and let it move away, keeping children and pets at a distance. Do not try to catch or kill it. If it is inside a house or in a risky place, contact a trained snake rescuer or the forest department.
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