Diamondback Water Snake: Care & Feeding Tips for Beginners

Have you ever seen a SNAKE in the water and wondered – “What was that?!”

Or, even scarier – “Is it a water moccasin???”

Well, we have two reassuring facts for you:

  1. It’s more likely that it was a harmless water snake, like the diamondback water snake that you’ll learn about today.
  2. Even if it was a water moccasin, you were still likely safe. They want nothing to do with people and tend to be just as scared of us as we are of them.

Diamondback water snakes (Nerodia rhombifer) inhabit the central United States, especially the Mississippi River valley.

Keep reading to learn more about this beautiful, water-loving snake.

Facts at a Glance

Common Name

Diamondback Water Snake, Diamond-Backed Water Snake

Scientific Name

Nerodia rhombifer

Adult Size

30-48”

Native Range

Central United States and Northern Mexico

Lifespan

10 Years

Natural Diet

Fish, amphibians, aquatic invertebrates, small rodents

Natural Habitat

Banks of slow-moving bodies of water

Do They Make Good Pets?

Yes

Minimum Enclosure Dimensions

36” x 12” x 16”

Temperature

Warm Side: 80-86

Cool Side: 68-74

Natural History: What Are Diamondback Water Snakes?

The diamondback water snake (Nerodia rhombifer), or diamond-backed watersnake, is an aquatic species native to central North America.

They’re a part of the genus Nerodia. Their popular relatives include other North American water snakes, like:

North American water snakes
A close relative of the Diamondback Water Snake, the Northern Water Snake (Nerodia sipedon).
  • Green water snakes
  • Brown water snakes
  • Banded water snakes
  • Common water snakes

Many people tend to mistake a diamond-backed watersnake for a venomous cottonmouth. Their dark brown coloration and water-loving habits throw folks off!

Luckily, diamondback water snakes are non-venomous and harmless. They may bite, draw blood, or even poop on you – but it’s nothing more than an unpleasant encounter!

Native Range and Habitat

The diamond-backed watersnake lives primarily in the Mississippi River valley, but its range also extends throughout central North America, including:

  • Iowa
  • Texas
  • Illinois
  • Indiana
  • Kansas
  • Georgia
  • Missouri
  • Alabama
  • Arkansas
  • Louisiana
  • Oklahoma
  • Tennessee
  • Mississippi
  • Northern Mexico

They prefer to live along slow-moving bodies of water, like streams, rivers, ponds, and swamps.

It’s not uncommon to find a diamond-backed watersnake in urbanized areas, as long as there’s water and fish.

Conservation

Wild populations of diamondback water snakes are thriving and healthy.

Unfortunately, the biggest threat to their population is humans.

Since people often mistake these harmless snakes for venomous snakes like cottonmouths, they tend to ignorantly kill them on sight. 

diamondback water snakes
People often mistake harmless diamondback water snakes for venomous cottonmouths. Neither species should be disturbed or harmed in the wild.

Size and Appearance

Adult Length: 30-48”

Adult Weight: 200-600 grams

The record length for a diamondback water snake was 69 inches.

Brown or dark olive green Diamondback water snakes
This young diamondback water snake shows the vaguely diamond-shaped pattern and lighter coloring of juveniles.
Credit: u/Genetics (via Reddit.com)

Diamondback water snakes are heavy-bodied snakes that are dark brown or dark olive green.

They have dark blotches connected by alternating dark bars that create an intricate, diamond-shaped pattern.

Their bellies are yellow or light tan with dark blotches.

Their scales are keeled (raised), creating a rough and bumpy skin texture.

Temperament and Behavior

Like most water snakes, wild diamondback water snakes are notoriously grumpy.

If you attempt to catch one, it will likely bite you and poop on you.

Their feces and musk are particularly potent-smelling, due to their fish-based diet.

To add insult to injury, their saliva contains a mild anti-coagulant that will cause you to bleed a surprisingly large amount for such small puncture wounds.

Still, even the largest diamondback water snake is NOT capable of inflicting any serious injury.

Alabama black water snake on log
Wild Nerodia species prefer to bask right on top of – or next to – a body of water.

When undisturbed, wild diamondback water snakes frequently bask on branches suspended over a body of water.

They even hang down and dip their head under the water’s surface to hunt for fish and amphibians!

When startled, a basking diamondback water snake will drop down from the branch into the water and swim away.

Lifespan

Neither the captive nor the wild lifespan of diamondback water snakes is well documented.

It’s believed that they live for around 9 to 10 years, on average.

Diamondback Water Snake vs Cottonmouth

Many people who aren’t familiar with native snake identification mistake diamondback water snakes for cottonmouths, also known as water moccasins.

Once you learn what to look for, it should be easy to tell the difference.

water snake in water
Water snakes have round pupils and googly eyes.

Pupils: Diamondback water snakes have round pupils.

Cottonmouths have vertical, cat-like pupils.

Pattern: Diamondback water snakes have a diamond-like pattern.

Cottonmouths have a triangular, Hershey’s kiss pattern.

Cottonmouth snake on dead leaves
Here you can see the triangular, bulls-eye pattern and brow ridge of a cottonmouth.

Eye Shape: Diamondback water snakes have almost cartoon-like round eyes that give them a harmless, goofy expression.

Cottonmouths have a prominent brow ridge above their eyes, making them look “angry” or “mean” at all times.

Typical water snake closeup
This photo depicts the labial bars present on water snakes’ mouths.

Labial Bars: Diamondback water snakes have connected, alternating dark bars on their “lips” (upper and lower).

Cottonmouths have a yellow lower jaw with irregular dark blotches.

Eye Bar: Diamondback water snakes have a fairly uniform dark brown or dark olive-green head.

Cottonmouths have a dark band extending from the back of each eye. Some people call it a “Zorro mask”.

Are Diamondback Water Snakes Poisonous?

No, the diamondback water snake is not poisonous or venomous.

Technically, most snakes aren’t poisonous.

A poison is a toxin that you must ingest. Poison dart frogs are a perfect example. Some snakes are actually poisonous, but since we humans don’t typically eat snakes, it’s not a huge concern.

Many snakes are venomous—such as the blunthead tree snake—but NOT the diamondback water snake.

Venom is a toxin that must be injected into or otherwise enter the bloodstream. Since some snakes inject their toxin when they bite, they are venomous. Bees are also venomous, since they must sting to deliver their toxin.

Diamondback Water Snake Husbandry: How to Care for This Aquatic Species

Supply List

  • Large water dish
  • Heating pad or heating lamp
  • 30-gallon glass aquarium (or larger)
    • Secure lid with locking clamps
  • At least two appropriately-sized reptile hiding decorations

Enclosure Size and Style

Minimum Enclosure Size: 36” x 12” x 16”

Ideal Enclosure Style: Glass or acrylic aquarium, plastic tub, PVC or sealed wood enclosure

Ideal Enclosure Setup: 50% water and 50% land

Realistically, you could set up your water snake’s enclosure like any other North American colubrid. They only need a water dish large enough to completely submerge in.

Since diamondback water snakes prefer an aquatic habitat, we highly recommend using a larger water dish that allows the snake to swim around.

When decorating the habitat, remember that snakes like clutter. Fill empty spaces with lots of rocks, leaves, plants, branches, and caves.

Heating

Ideal Warm Side Temperature: 80-86°F

Ideal Cool Side Temperature: 68-76°F

Ideal Night Time Temperature: 68-72°F

A reptile heating pad covering no more than 33% of the enclosure is the simplest solution for heating your diamondback water snake’s habitat.

A halogen light bulb offers more natural, deep-penetrating heat wavelengths.

Since you’ll need to turn it off every night, it also offers the benefits of a naturalistic nighttime temperature drop.

In either case, you should always run heating elements on a thermostat.

A simple on/off thermostat will work for heat pads, but you’ll need a proportional or dimming thermostat for a heat lamp.

Lighting

Ideal Lighting Cycle: 12 hours day/12 hours night

If you’re using a halogen light bulb, you’ve already got your snake’s day and night cycle handled! Just be sure to turn it off for 12 hours in every 24 hour period.

Otherwise, regular lighting from a lamp in the room, or even sunlight through the window, can serve as your snake’s lighting.

While it’s not necessary, scientists continue to prove that offering UVB lighting to captive snakes is beneficial.

Water and Humidity

Ideal Humidity: 40-60%

Death Adder with opaque spectacle prior to sloughing
This death adder has opaque, milky-blue eyes that signal that it’s getting ready to shed.

Aim to bump up the humidity when your snake is entering its shed cycle. Key signs include reduced pattern, darker colors, and milky-blue eyes.

Alternatively, you can offer a “humid hide” – cut an entrance into an appropriately-sized plastic box and fill it with damp sphagnum moss. Be sure to smoothen any sharp edges.

As its name suggests, your diamondback water snake will prefer to spend much of its time in the water.

Offer a water feature that’s deep enough for your snake to fully submerge itself, and allow it as much space as possible to swim and move around in the water.

Since your diamond-backed watersnake will spend so much time in the water, be sure to wash the bowl and replace the water every single day.

Your water snake will likely track substrate into the water when entering and exiting. They also prefer to defecate in the water, which gets gross fast.

Decor and Environmental Enrichment

Your diamondback water snake’s enclosure should feature at least two hiding opportunities, but more is better. Here are some ideas to get you started, but feel free to get creative:

  • PVC pipes
  • Reptile caves
  • Cardboard tubes
  • Fake or live plants
  • Cork bark rounds, half-rounds, and flats

Remember: wild diamondback water snakes like to bask and dangle from branches hanging over a body of water.

Make an effort to replicate this by including a branch in your diamondback water snake’s enclosure. Bonus points for positioning it above their water container!

Substrate

Great Choices:

  • Coconut husk
  • Coconut fiber
  • Cypress mulch
  • Sphagnum moss
  • Organic topsoil mixed with washed play sand

Avoid:

  • Newspaper
  • Calcium sand
  • Reptile carpet
  • Pine, cedar, or aspen shavings

Diamondback Water Snake Baby Care and Appearance

baby diamondback water snake
This baby diamondback water snake is likely a few months old.

Did you know that diamondback water snakes give live birth?!

That’s right! Instead of laying eggs, these snakes give live birth to litters of approximately 50 babies. This method of reproduction is known as ovoviviparous.

Diamondback water snake babies look just like miniature versions of their parents. Usually, their color is somewhat lighter and their pattern is more pronounced.

Caring for a baby diamondback water snake is much the same as caring for an adult. Keep the following things in mind:

  • They’re small! Ensure that the enclosure you house them in has no ventilation holes or openings that are large enough for your baby snake’s head to fit through.
  • They’re picky eaters. Baby diamondback water snakes are much less likely to accept rodents than adults. Fish almost always work, just be sure to avoid vitamin deficiencies (see the diet section below).
  • They’re more sensitive to heating and humidity fluctuations. Be sure to set up your new baby’s enclosure before you bring it home. Ensure that the habitat parameters are optimal and stable.

Diamondback Water Snake Diet: Slippery Fish and Other Aquatic Prey

Diamondback water snakes will eat:

  • Fish
  • Rodents
  • Crayfish
  • Amphibians
Common Watersnake eating fish
This common water snake is eating a large tadpole.

In captivity, try to avoid feeding goldfish or rosy red minnows. Both of these fish contain thiaminase, which hinders your water snake’s ability to absorb vitamin B.

Guppies are your best bet when it comes to live fish.

Slivers of fresh salmon, trout, and other seafood work as occasional treats, too. Without the bones, they don’t have the proper calcium:phosphorus ratio for a staple diet.

Most water snakes will eventually transition to eating rodents in captivity, but they don’t have to.

Do Diamondback Water Snakes Make Good Pets?

Diamondback water snakes make great pets for snake lovers.

They’re active, inquisitive, and outgoing. They stay relatively small and easy to handle. Their beautiful pattern makes it hard to believe they’re not rare and exotic!

Although some may prefer to eat fish at first, most water snakes aren’t picky eaters for very long.

Have you ever owned a water snake before? Tell us about it in the comments below.

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