Diamondback Terrapin Species Profile

Characteristics, Housing, Diet, and Other Information

Diamondback terrapin
Clara S. / Flickr / CC By 2.0

"Terrapin" is an Algonquian Indian word roughly meaning “little turtle," and diamondback terrapins are named for the diamond-shaped pattern on their carapace (dorsal shell); they are one of the most beautiful turtles native to the United States. Diamondback terrapins are fairly docile turtles that are generally willing to be handled, although they may nip if they feel threatened. These are small aquatic turtles that live in unexpected habitats along the Eastern and Gulf coasts of the U.S. You can observe them in shallow waterways from Cape Cod, Massachusetts through the Florida Keys and westward to the coast of Eastern Texas. (A small group of diamondbacks also lives in Bermuda.) They differ from other common pet aquatic turtles, like the painted turtles and red-eared sliders, because they inhabit brackish (partial salt) water instead of purely freshwater.

Species Overview

Common Name: Diamondback terrapin, terrapin

Scientific Name: Malaclemys terrapin

Adult Size: Females grow up to 8 inches; males grow to 5 inches

Life Expectancy: 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

These turtles are social and prefer the company of members of their immediate family like parents and siblings. They are known to share resources, like piling atop one another to concurrently take advantage of the best basking rock.

During the day, they enjoy basking in the sun (or under a heat lamp), often in social groups, so be sure you have enough space for your pets. You can raise a single turtle successfully, but diamondbacks are fairly social and do even better in groups—provided there is enough space for everyone. Chronically over-crowded diamondbacks may nip at one another's tails.

Housing the Diamondback Terrapin

Your pet terrapins will require brackish water in captivity that matches what that subspecies experience in the wild. Owners who attempt to keep captive terrapins in unsalted freshwater usually end up switching back to brackish once the turtles begin exhibiting health problems from the lack of salt.

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. Look for a 75 gallon or larger tank that will allow your turtle to dive and swim.

As aquatic turtles, diamondback terrapins need a tank filled with brackish water that is deep enough for the turtle to swim and dive in comfortably. Aim for a water depth that is at least three times as deep as the length of the turtle's current shell. They'll also need a wide, flat place to haul out of the water for comfortable group basking.

Water filtration is crucial to a diamondback terrapin's environment as these messy eaters usually create dirty water that will lead to skin and shell problems including shell rot. There is a variety of submersible, canister, and traditional water filters to choose from.

Crushed coral is recommended for the bottom of the tanks. It serves a dual purpose as both a substrate (tank flooring) and a calcium supplement. Diamondback terrapins like to bite at the coral, and they benefit from both the added calcium in their diet and the natural wear to their beaks as they crunch it.


Terrapins don't need terribly warm water (above 70 F will do) but they do need to be kept from getting too cold. During the day, white heat lights can be used to add extra warmth to your tank, but at night, use a ceramic heat emitter with only blue or red light. Water heaters designed for fish tanks can also be used to keep the water warm, but make sure the ambient temperature in the air of the enclosure is kept around 80 F.


Like other aquatic turtles, terrapins require UVB lights. UVB spectrum lights that are specifically designed for reptiles should be kept on for about 12 hours a day and positioned roughly 10 to 12 inches from where the turtle basks. This will enable your beautiful terrapin to grow, stay strong, and properly convert the vitamin D into the usable form in its body. Without UVB light, your turtle is extremely likely to develop metabolic bone disease (MBD) 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 aquatic animals, while they do graze on some plants. In captivity, you can feed them whatever they will eat of a mix of turtle pellets, dried shrimp, smelt, snails, and other accessible seafood over a 20 minute period. Feed every other day, once during that day.

Do not feed them meat such as chicken or beef; if they don't encounter the food in the wild, a diamondback terrapin probably won't be able to digest it easily. As turtles go, terrapins are rather messy eaters that will often turn over their food bowls to enjoy eating when and wherever they choose. 

Common Health and Behavior 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 deformities of either the shell or the eye. All of these can occur when the turtle is under stress, receives poor nutrition, or lives 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 a ppm (parts per million) concentration of saltwater that mimics the natural origin of the subspecies you have.

Choosing Your Diamondback Terrapin

When buying one or more diamondback terrapins, choose young turtles that are available from reliable turtle breeders. Young terrapins are usually gray above with lighter colors below.

While it's possible to find diamondback terrapins in the wild, they are usually quite anxious and don't make very good pets. Worse yet, the stress created by captivity will cause early health problems in most wild-born diamondbacks.

Similar Species to the Diamondback Terrapin

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Otherwise, check out other types of aquatic turtles that can be your pet.