Housing Aquatic Turtles

By Gregory Rich, DVM; Laurie Hess, DVM; Rick Axelson, DVM

Aquatic turtles are referred to as turtles, terrapins, or chelonians. For this discussion, the common and popular red-eared slider will be used as a representative for a pet aquatic turtle to describe proper housing. Improper environment and poor nutrition are the most common causes of health problems encountered in reptiles. Properly housed and turtles fed nutritionally balanced diets grow rapidly and are healthier and happier.

What type of cage does my red-eared slider require?

Aquatic turtles should be kept in an aquarium that is as large as possible. As your turtle grows, so does the need for a larger enclosure, so it is better to start juvenile, growing turtles in a large tank right from the start. The aquarium should have enough water for the turtle to swim, a dry area where the turtle can escape the water to bask, a heat source, and a source of ultraviolet (UV) light.

Aquatic turtles require enough water that they can swim fully submerged. Some minimum guidelines suggest the depth of the water should be at least 1.5 to 2 times the shell length of the turtle, and the length of the swimming area should be 4 to 6 times the shell length. Another suggested minimum is 10 gallons of water per inch of shell length, plus a basking or dry zone that is 15% to 25% of the surface area.

The dry landing place should be large enough to allow the turtle to climb completely out of the water. A large rock or a secure stack of smaller rocks with a flat top works well. The landing place should be easily accessible to the turtle and should be at the same end of the tank as the basking lamp. A submersible fish tank heater should be used to heat the water to a temperature of 75ºF-82ºF (24ºC-29ºC). An aquatic thermometer can be used to regularly monitor water temperature changes.

"Clean water is crucial to optimal turtle health."

Clean water is crucial to optimal turtle health. Since pet turtles eat and eliminate in the same water, the tank water must be changed at least once weekly, or more frequently if it becomes dirty. To maintain a relatively constant, normal bacterial flora in the water, many turtle owners change 50% of the water every week. On the third or fourth week, they empty the entire aquarium and clean it thoroughly. Other people do not recommend partial water changes but empty all the water at once to change it.

Regardless of how water changes are done, ensure the water is warmed up before reintroducing the turtle to a newly cleaned tank. Abrupt water temperature changes can affect the turtle’s immune system function and ability to digest food, ultimately leading to disease. A good quality water filter can be used to keep the water clean between changes. Some of the better, more powerful filters pump the water out of the tank, process it and return it to the tank. Feeding your red-eared slider in a separate "feeding tank" also helps reduce food debris from building up in the turtle’s main aquarium.

What else do I need in the aquarium?

Turtles are ectothermic, meaning their body temperature is regulated by their environmental temperature. Environmental temperature affects a turtle’s activity level, as well as their immune system function and the ability to digest food. Turtles will be less active in cooler temperatures and more active when it is warmer. You will need a heat source in the tank to establish a temperature gradient, with one end of the tank warmer than the other end. In this way, the box turtle can move around its environment and warm or cool itself, as it needs to.

A focal heat source can be provided using a 100-watt incandescent bulb with a reflector hood, with a commercially available heat lamp, or with a ceramic heating bulb. Heat sources should be placed outside and above one end of the aquarium, over the dry basking area, so that the turtle cannot directly contact them and accidentally get burned. The basking area temperature, monitored daily with a thermometer, should be 75ºF-88ºF (24°C-31ºC).

The goal is to provide a hot basking area and a cooler area, far away from the basking area, such that the turtle can regulate its body temperature by moving through the temperature gradient. At night, when the turtle is sleeping, lights should be turned off, and extra heat may not be required, as long as the water temperature does not fall below 65ºF-70°F (18°C-24°C). Sustained lower temperatures may cause the turtle to stop eating and may make the turtle more susceptible to bacterial infections.

"Sustained lower temperatures may cause the turtle to stop eating and may make the turtle more susceptible to bacterial infections."

Plants can be used for decoration if they are safe for the turtle to eat. Plastic plants can be dangerous if the turtle attempts to eat them. Speak to a knowledgeable pet store employee or veterinarian about safe plants. If you are unsure if a plant is safe, do not use it in your turtle’s tank. Stones may be used to line the bottom of the aquarium, but they must be smooth and too big to be eaten. Turtles have been known to swallow small stones, which can cause serious intestinal inflammation and/or blockage. If you use stones in the tank, they must be washed and cleaned frequently, as they accumulate algae, fecal material, and food debris, making them unsanitary over time. Avoid sand or gravel, as it is commonly ingested by turtles, leading to gastrointestinal tract obstruction.

Does my turtle need ultraviolet (UV) light?

A wild reptile may spend many hours a day basking in the sun, absorbing ultraviolet (UV) light. This spectrum of light is essential for their body in manufacturing vitamin D3, which the turtle needs for proper calcium absorption from their intestines. Lack of UV light can predispose your pet to metabolic bone disease (MBD). This common condition of pet reptiles occurs when reptiles do not absorb enough calcium from their diet, and instead, they extract it from their own bones, making the bones weak and likely to fracture. MBD is fatal if left untreated.

A UV light source should be in the UV-B range (290–320 nanometers) to prevent this condition. Most bulbs sold commercially for use with reptiles provide both UV-A and UV-B, but it is the UV-B part of the light spectrum that is critical to promoting proper calcium and phosphorus balance in a reptile’s body. The UV output of these lights decreases with age, so they should be replaced every 6 months or as directed by the manufacturer.

"For UV light to be effective, it must reach the pet in an unfiltered form, with no glass or plastic between the pet and the light."

For UV light to be effective, it must reach the pet in an unfiltered form, with no glass or plastic between the pet and the light. The light source should be within 12–18 inches (30 cm-45 cm) from the turtle for it to receive maximum benefit. Regular exposure to natural, direct sunlight outside (unfiltered through glass) is ideal and recommended whenever the climate permits. Outdoor temperatures above 80°F (27°C) are best for proper UV absorption. Be sure that when a turtle is outdoors, it is provided with a shaded area to escape from the sun if it chooses. Also, be sure to supervise your turtle outside to prevent escape or attack from wild animals.

Consult a veterinarian familiar with reptiles if you have any questions or concerns about proper lighting or housing for your red-eared slider. Thoroughly wash your hands after feeding, cleaning, or handling turtles, as they can carry and transmit Salmonella bacteria.

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