Discover the Largest Diamondback Water Snake Ever Found

Diamondback Water Snake - On Rocks
© Rusty Dodson/

Written by Taiwo Victor

Updated: August 31, 2023

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There are animals on Earth whose names leave little to the imagination – and the diamondback water snake is one such. Just as its name suggests, this species is often found in aquatic habitats and is identified by the chainlink pattern of its scales. Diamondback water snakes are large, thick-bodied snakes, with most adults about 3 feet in total length! In fact, they are considered the largest water snake species in North America. So, just how big do they get? Read on to find out! 

Background on Diamondback Water Snake

The diamondback water snake is a common nonvenomous colubrid snake endemic to the central United States and northern Mexico. It belongs to the Nerodia genus, consisting entirely of species native to North America.

There are three recognized subspecies – Nerodia rhombifer blanchardi, Nerodia rhombifer rhombifera, and Nerodia rhombifer werleri.


Diamondback Water Snake

The diamond-shaped pattern and brown coloration often cause it to be mistaken for rattlesnakes.

©Laurie L. Snidow/

The diamondback water snake is stout-bodied and brown, light grayish-brown, dark brown, or dark olive green, with a black net-like pattern along the entire back in a diamond-shaped pattern. This pattern is formed by dark vertical bars connected to alternating rows of dark blotches often present down the snake’s sides. The diamond-shaped pattern and brown coloration often cause it to be mistaken for rattlesnakes, especially when the diamondback water snake is encountered on land. However, the belly is generally yellow or light brown with black half-moons. Adult males have multiple tubercles under the surface of the chin, a characteristic found only on this species of snake in the United States.

Diamondback water snakes have 25-31 scale rows at their midbody. The dorsal scales are strongly keeled, with each scale having a prominent raised ridge, giving them a rough texture. Juveniles of this species look similar to adults, though neonates appear lighter in color and their patterns are more pronounced.

Range and Habitat

Diamondback water snake

Spread across the United States, the diamondback water snake is predominantly found along the Mississippi River valley.

©Seth LaGrange/

As one of the commonest snake species within its range, the diamondback water snake’s range extends from the United States (especially the central U.S.) to northern Mexico. Spread across the United States, it is predominantly found along the Mississippi River valley and beyond the states of Oklahoma, Texas, Kansas, Louisiana, Iowa, Arkansas, Illinois, Missouri, Indiana, Mississippi, Tennessee, Alabama, and Georgia. It extends to northern Mexico, in Nuevo León, Coahuila, Veracruz, and Tamaulipas.

As its name suggests, it is often encountered close to slow-moving bodies of water such as rivers, streams, swamps, or ponds. They can be found in various freshwater habitats in other parts of their range. However, diamondback snakes prefer bodies of water with overhanging vegetation. 


The diamondback water snake is often found hanging on branches suspended over water when foraging for food. It dips its head under the surface of the water and continues to do so until it encounters prey. If cornered, this snake will often hiss and flatten its body to appear larger. It only resorts to biting if handled or physically harassed. The diamondback water snake’s bite is quite painful due to its sharp teeth, which can make the bite wound bleed more profusely. This defensive behavior causes this species to be frequently mistaken for the venomous cottonmouth with which it shares the same habitat. 

"Largest" infographic for the biggest diamondback water snake ever found.
Diamondback water snakes are endemic to the southern US and northern Mexico.

The maximum record length for the diamondback water snakes is 5.75 feet (180 cm), found in the southern states.

The diamondback water snake is large and stocky, with most adults reaching a total length (including tail) of 3 feet to 5 feet (91 to 152cm). On average, female diamondback water snakes tend to be slightly larger and heavier than males of the same species.

What do They Eat?

Diamondback water snakes are carnivorous, primary piscivores by nature. They feed almost exclusively on freshwater fish, rodents, toads, frogs, salamanders, minnows, crayfish, and sometimes young turtles. They do not constrict prey; instead, they overpower prey by grabbing it in their jaws and swallowing it alive after it has been subdued. In addition, they are typically nocturnal but may become diurnal during the spring and fall. Diamondback water snakes like to wrap themselves on low branches that overhang the water. They dip their heads under the water, and when a fish passes by, they strike out to grab it.

brown watersnake

Diamondback water snakes aren’t considered dangerous to people and pets because they only bite when threatened.

©Rusty Dodson/

Do They Bite?

Diamondback water snakes are non-venomous and not dangerous to people or pets. These docile snakes are not aggressive; they avoid direct contact with people. Although they will readily bite to defend themselves, almost all bites occur when the snakes are intentionally bothered. Even though the diamondback water snake will typically flee into the water and swim away for shelter, it will bite if grabbed or cornered. They may also release fecal matter or a foul-smelling musk from a pair of glands in the base of the tail when handled. Nonetheless, these snakes are not aggressive and only strike or bite as a last resort. While they are not venomous, their bite can be painful as they have sharp teeth that are designed to bite deep into a fish and hold on.

In Captivity

Due to how common the diamondback water snake is, the species is frequently held in captivity even though they don’t have a lot of market value in the pet trade. When captured, they may bite, but they later become docile with regular handling. This snake feeds primarily on fish but must be supplemented with nutrients such as vitamin B1. If you intend to keep this snake as a pet, be aware that they often have a very offensive smell, probably because its diet consists mostly of fish. They also use this smell as a defensive measure and will excrete a foul-smelling substance to help drive off their attacker.

Conservation Status 

The diamondback water snake is currently classified as “Least Concern” on the IUCN Red List. The species is widespread throughout its range and its population today is stable. Even though the diamondback water snake is not significantly endangered or threatened, human ignorance is the main threat to this species. Because of its striking resemblance to the cottonmouth or rattlesnakes, it is often killed out of fear, leading to the death of hundreds of diamondback water snakes each year. In addition, they also face the destruction and degradation of their aquatic habitat.

Other Record-Breaking Snakes

Smallest Snakes: Barbados Thread snake

The diminutive Barbados Thread snake might easily be mistaken for an


and can comfortably curl up on a U.S. quarter.

©John Oldale / CC BY-SA 3.0 – Original / License

There are several snakes in the world that have broken records. For example, the longest snake ever kept in captivity was a reticulated python (Python reticulatus) named “Medusa.” Medusa was 25 feet long and weighed 350 pounds! The heaviest snake ever recorded is an African rock python (Python sebae), which weighed 403 pounds! Other record-breaking snakes include the longest venomous species – King Cobra (Ophiophagus hannah). This particular specimen measured 18 feet 8 inches in length!

The Guinness Book of World Records also recognizes some other interesting categories for snakes, such as “the most venomous” or “the smallest.” Interestingly, one of the smallest species of snakes is Leptotyphlops carlae – commonly known as Caribbean threadsnake. It measures just 4 inches when fully grown and can easily fit on a US quarter coin. On the other hand, one of the most venomous species is Inland Taipan (Oxyuranus microlepidotus), native to Australia. Its venom contains neurotoxins which can kill humans within 45 minutes if left untreated – making it potentially one of the deadliest creatures on Earth.

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About the Author

For six years, I have worked as a professional writer and editor for books, blogs, and websites, with a particular focus on animals, tech, and finance. When I'm not working, I enjoy playing video games with friends.

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