Most snakes found in Chennai homes during the monsoon are harmless. On one heavy-rain day in November 2020, the city’s wildlife headquarters rescued 33 rat snakes and 27 cobras, along with wolf snakes and keelbacks, but only four kraits and three Russell’s vipers, DT Next reported. In the 2015 floods, bronzebacks and rat snakes made up most of the rescues.
India has about 310 snake species, 66 of them venomous, according to the Health Ministry’s national snakebite action plan. Tamil Nadu alone has 142, the Forest Department said at the NAAGAM app launch in 2025. This guide covers the species you are most likely to meet in the city, how official guides describe the dangerous ones, and why you should never stake a life on your own identification.
A warning first
The Health Ministry’s human-snake conflict guidelines warn that appearance alone is unreliable because some harmless snakes mimic venomous ones. Use this guide to stay calm and describe what you saw, not to decide whether a bite needs treatment. Every bite goes to hospital. First aid steps and free antivenom are covered in our separate snakebite guide.
The four that matter
Most serious bites in India come from the “Big Four”. The Health Ministry’s guide to medically important snakes gives these field marks:
| Snake | Typical size | Key features |
|---|---|---|
| Spectacled cobra (nalla pambu) | 120-150 cm | Slender, even thickness; yellow-brown in the south with faint marks; raises a hood when threatened; rounded snout |
| Common krait | About 100 cm | Glossy bluish-black with paired milky-white bands; plain creamy belly; enlarged hexagonal scales along the spine; all-black eyes |
| Russell’s viper | 100-120 cm | Thick body; triangular head wider than neck; three rows of round or almond blotches on brown; vertical pupils |
| Saw-scaled viper | Under 60 cm | Small and stout; rough keeled scales; white wavy lines along the sides; a plus-shaped mark on top of the head |
The national plan adds a general rule. Cobras and kraits are long, thin and fairly uniform in colour. Vipers are thick and short, with rough scales on the head and bold patterns. All four are on show at the Chennai Snake Park in Guindy, which in March 2025 held 11 cobras, 4 kraits, 6 Russell’s vipers and 9 saw-scaled vipers. A visit is the safest way to learn them.
The harmless ones you will see most
- Rat snake (dhaman). Long, fast and brownish, often in gardens and drains. It eats rodents and tends to avoid cobras, the guidelines note. It is the snake most often mistaken for a cobra.
- Checkered keelback. The common water snake of ponds, canals and flooded plots, olive with a dark chequer pattern. The guidelines list it among the most frequently rescued snakes. It bites readily but is not venomous.
- Common bronzeback (komberi mookan). Thin, brown and quick, living in hedges and trees. It was the most common rescue in the 2015 floods, The News Minute reported.
- Common wolf snake. Small, brown-black with pale bands. It looks like a krait and suffers for it. Its bands are narrower and its scales lack the krait’s raised spine row.
- Sand boas. Thick, slow and blunt-tailed, often confused with Russell’s viper. The common and red sand boas are both held at the Guindy park.
- Vine snake. Bright green and thread-thin with a pointed snout, found in garden shrubs. It is not regarded as a danger to people.
Lookalike pairs to remember
Three pairs cause most of the confusion in Chennai homes:
- Cobra and rat snake: only the cobra spreads a hood. A rat snake inflates its throat but never forms a flat hood.
- Krait and wolf snake: the krait’s white bands come in pairs on glossy blue-black. A wolf snake is browner and smaller.
- Russell’s viper and sand boa: the viper has a clear triangular head and a chain of blotches. A sand boa’s head is barely wider than its neck.
Kraits deserve special care because they are active at night and bites can be nearly painless. Use a torch on paths after dark and avoid sleeping on the floor in ground-floor homes during floods.
Keeping snakes out
The Health Ministry guidelines suggest sealing gaps under doors and drain outlets, filling rat holes, controlling rodents and toads, storing firewood and bricks away from the house, and fitting mesh on low windows. If a snake does get in, leave the room, shut the door and call the Forest Department or use the NAAGAM app, launched in 2025 to connect residents with trained rescuers.
Quick answers
Which snakes in Chennai are venomous?
The ones that matter are the spectacled cobra, common krait, Russell’s viper and saw-scaled viper. Most others seen in homes are harmless.
Is the water snake in my sump dangerous?
Usually it is a checkered keelback, which is non-venomous. Still, do not handle it. Call a rescuer.
Can I tell from the bite marks?
Not reliably. Go to hospital for every bite.
Where can I see these snakes safely?
The Chennai Snake Park in Guindy, which is closed on Tuesdays.
Information checked against official sources on 18 October 2026. Fees, dates and rules can change; confirm on the linked official pages before acting.
Sources
- Medically important snakes of India (NCDC, Ministry of Health and Family Welfare)
- Guidelines for Mitigating Human-Snake Conflict (NCDC, Ministry of Health and Family Welfare)
- National Action Plan for Prevention and Control of Snakebite Envenoming (NCDC)
- Chennai Snake Park Trust Annual Report 2024-25 (Central Zoo Authority)
- Rescue calls flood wildlife HQs as snakes slither into homes (DT Next, November 2020)
- Dangerous snakes slithering into homes in water-logged areas (The News Minute, November 2015)
- Tamil Nadu launches NAAGAM app on World Snake Day (Adyar Times, July 2025)
