Diamondback Terrapins

Active Aquatic Turtles for Your Home

Diamondback terrapin
Clara S. / Flickr / CC By 2.0

Diamondback terrapins are small aquatic turtles that live in different locations along the Eastern and Gulf coasts. You can observe them in shallow, brackish waterways from Cape Cod, Massachusetts through the Florida Keys and along Texas’ eastern coast. A small group of diamondbacks also lives in Bermuda. They differ from other common pet aquatic turtles, like painted turtles and red-eared sliders, because they live in brackish water. Diamondback terrapins are named for the diamond-shaped pattern on their carapace and are some of the most beautiful turtles native to the United States.

  • Name: Diamondback terrapin, terrapin, Malaclemys terrapin
  • Size: Females will grow up to eight inches long and males will be about five inches long\
  • Lifespan: Between 25 to 40 years in the wild 

There are actually seven subspecies of diamondback terrapins; they are similar to one another and require similar care, but each has a unique appearance. The ornate diamondback terrapin, for example, can be found in the wild in Florida; it has light yellow and orange coloring. The Texas diamondback terrapin, by contrast, has gray skin with dark speckles and a white or blue-gray head.

Diamondback Terrapin Behavior and Temperament

Diamondback terrapins are fairly docile turtles that are generally willing to be handled (though they may nip if they feel threatened). During the day they enjoy basking in the sun (or under a heat lamp), often in social groups. They are rather messy eaters, and will often dump their food bowls to enjoy eating when and wherever they choose. 

Housing the Diamondback Terrapin

Pet terrapins require brackish (slightly salty) water in captivity just as they do in the wild. Some owners of captive born Diamondbacks have also had success keeping their turtles in freshwater. Some owners who keep captive terrapins in freshwater end up switching to brackish water when their turtle ends up with health problems.

Since they're aquatic turtles, diamondback terrapins need a tank that is filled with brackish water that's deep enough for the turtles to swim and dive comfortably. They'll also, however, need a wide, flat place to get out of the water and on dry land. Look for a 75 gallon or larger tank that will allow your turtle to dive and swim and add a large flat rock or another surface for comfortable basking. While many owners use fish tanks for their diamondbacks, any large waterproof container will do—provided that the diamondbacks can't climb out, and other pets or objects can't climb or fall in.

Water filtration is crucial to a diamondback terrapin's environment. Dirty water will lead to skin and shell problems including shell rot. There are a variety of submersible, canister, and traditional water filters that you can choose from.

Crushed coral is recommended for the bottom of the tanks. It serves a dual purpose as both a substrate and a calcium supplement. Diamondback terrapins like to munch on the coral and they benefit from the added calcium in their diet and the natural wear they get to their beaks from eating it.

Light and Heat

Like other aquatic turtles, terrapins require both heat lights and UVB lights. They don't need terribly warm water (in the upper 70's will do) but they do need to be kept from getting too cold. This is where the heat lights come into play.

During the day, white heat lights can be used to add extra warmth to your tank, but at night you should use a ceramic heat emitter with blue or red light so you don't stress your turtle out with light during the nighttime. Water heaters designed for fish tanks can also be used to keep the water warm but make sure the ambient temperature outside of the water is kept in the 80's.

UVB lights specifically designed for reptiles should be kept on for about 12 hours a day and kept about 10 to 12 inches from where your turtle basks. This will enable your beautiful terrapin to grow, stay strong, and properly convert the vitamin D it takes in to use in its body. Without UVB lights your turtle will develop a metabolic bone disease and not grow properly.

Food and Water

Unlike most other pet aquatic turtles, diamondback terrapins primarily eat meat. In the wild, they eat a variety of small seafood and graze on some plants. In captivity, you can feed them turtle pellets, dried shrimp, smelt, snails, and other accessible seafood. But don't feed them meats such as chicken or beef; if they don't encounter a food in the wild, a diamondback terrapin probably won't be able to digest it easily. For new hatchings, provide a calcium block and cuttlebone for good nutritional health.

Common Health Problems

In general, diamondback terrapins are usually healthy and parasite-free. The most significant health problem for a diamondback terrapin is shell rot. Another risk for this species are shell or eye deformities. All of these can occur when the turtle is under stress, is receiving poor nutrition, or is living in water that is either too saline or too fresh. To avoid these issues, choose healthy baby diamondback terrapins born in captivity, provide a varied and nutritious diet, and use brackish (mildly salty) water which mimics their natural habitat.

Choosing Your Diamondback Terrapin

When buying one or more diamondback terrapins, choose baby hatchlings made available from reliable turtle breeders. These adorable little turtles are usually gray above with lighter colors below. While it's possible to find wild diamondback terrapins in the wild, they are usually more anxious and don't make very good pets. Worse, the stress created by captivity can cause health problems for wild-born diamondbacks.

Be sure you have enough space for your pets. You can raise a single turtle successfully, but diamondbacks are fairly social and do well in groups—provided there is enough space for everyone. Crowded diamondbacks will nip at one another's tails.

Similar Breeds to the Diamondback Terrapin

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