Aquatic turtles need a setup that is similar to that used for aquarium ﬁsh. Therefore, the equipment you’ll need to house aquatic turtles can be found at any aquarium shop.
The ﬁrst requirement is a tank that is big enough for your turtles. Although they will spend most of their time basking lazily, aquatic turtles are active swimmers and need lots of room. Juvenile turtles will need at least a 10-gallon tank. Adult turtles need a minimum of 20 gallons per turtle. The larger the tank, the better. It is best to use the low or breeder style of aquariums, since these maximize the available surface area.
A few turtle species can live in a true aquarium—all water without any land to crawl out on. These include Musk and Mud turtles, Softshells, and Matamatas. Setting up a suitable tank for these species is simplicity itself: All you need is a tank of suitable size and, for the smaller Mud and Musk turtles, an underwater rock cave for hiding and sleeping. Adult Mud and Musk turtles will have enough space in a 10-gallon tank.
In the wild, Mud and Musk turtles prefer areas with thick, muddy bottoms. In captivity, such a setup with substrate at the bottom of the tank, even gravel or stones, traps dirt and detritus and makes it more difﬁcult to keep the tank clean. This means that despite their preferences, the bottom of the tank should be bare.
Ironically, these aquatic species (with the exception of Softshells) are not very good swimmers. They move around by walking along the bottom of the tank, so you must make sure to maintain the water at a proper depth. These species prefer to rest on the bottom of the tank and occasionally extend their nose to the surface, like a snorkel, to breathe. They cannot easily swim to the surface to breathe and can drown if the water is too deep for them. The water in their tank should therefore be deep enough to cover them completely, but shallow enough to ensure that every turtle can reach the surface with his nose.
The other aquatic turtles are strong swimmers and need a large, deep water area where they can swim and exercise properly. The water should be at least as deep as the shell of the turtle is long, and for strong swimmers, such as Painted turtles and Sliders, it should be much deeper, allowing plenty of room for swimming and exercise.
Most aquatic turtles are amphibious and will need a land area in their tank where they can bask and dry off. This is important for both thermoregulation and to prevent a buildup of fungus on the turtle. This basking area should be at one end of the tank and must be big enough to allow all the turtles in the tank to bask at the same time, but should not cover more than one-third of the tank area. That means if you have several turtles, you will need quite a large tank.
There are several ways to set up a suitable basking area. Perhaps the easiest is to pile up a number of ﬂat rocks at one end of the tank so they form an underwater cave below and protrude above the surface to provide a dry area for basking. Line this area with a moss substrate to prevent the turtles from injuring their plastrons on sharp edges as they climb on and off the basking platform. Make sure you stack the rocks very securely, so they will not wobble or tilt as the turtles climb on them.
A second alternative is to cut a piece of wood just big enough to ﬁt inside the tank at the water level and use thin wedges of wood to press it tightly against the edges of the tank to carry it in situ. One potential problem with this kind of basking area, however, is that the wood may become waterlogged and swell up, pushing apart the sides of the tank and perhaps causing leaks.
Whatever material you use, it is important that the land tilt gently into and beneath the water surface to allow the turtles to easily climb out. It is very difﬁcult for turtles, especially young ones, to clamber onto a land surface that is above or level with the water unless there is a submerged section at the shore for them to push off from.
Some hobbyists house their turtles in an aquavivarium, in which one half of the tank is open water and the other is a landscaped dry area, using soil or some other substrate. The land and water areas can be separated by a strip of glass or a clear plastic sheet glued across the tank with silicone aquarium sealer and extending about two-thirds of the way up the sides of the tank. The larger side of the tank is then ﬁlled with water, up to the level of the dividing barrier (as in the true aquarium, no substrate should be used in the water area of the tank). The smaller portion is ﬁlled with substrate and then landscaped as a natural terrarium. Several ﬂat rocks or pieces of wood are placed to form a ramp so the turtles can climb out of the water. These soil setups, while attractive, are not easy to maintain because they need frequent cleaning. If the soil is covered with a layer of moss, it will help prevent the turtle from dragging dirt into the water.
Aquarium gravel should not be used, because it has sharp edges that will make small cuts in the turtle’s plastron and could lead to infection. Rounded river gravel could be used instead, but the rounded pieces will constantly get pushed into the water.
The aquatic turtle tank has two separate areas—the water and the dry basking area and both need to be heated. Each must be considered separately.
Heating the Water
Some of the northern species of aquatic turtles, such as Musk turtles and Painted turtles, will do ﬁne if the water is kept at ordinary room temperature, so you will not need a heater for the water area of the tank. Other species, however, including Sliders, Reeve’s turtles, and Matamatas require somewhat higher temperatures, and the water portion of their aqua-terrarium must be heated.
The best equipment for this task is the submersible water heater commonly used in tropical ﬁsh tanks. This is a glass tube that contains an electrical heating element and a thermostat. It attaches to the lip of the tank and extends into the water. The output of this kind of heater is usually controlled by a small knob or dial at the top. For most aquatic turtles, a water temperature of 75 to 78 degrees Fahrenheit is suitable.
The fragility of these heaters poses a safety problem. Swimming turtles commonly knock the heater against the aquarium glass and crack it, or even attempt to climb up the heater tube and pull the whole thing into the water, presenting a serious electrocution hazard.
To guard against this, turtles must be prevented from physically touching the glass tube. The best way to do this is to surround the heater with a large pile of rocks that allows water to circulate around it while at the same time screening the heater from the turtles. Another method, which can be used if the tank has a large power ﬁlter (as indeed it should), is to place the heater in the ﬁlter box instead of the main tank, so the heated water ﬂows from the ﬁlter back into the aquavivarium. Since most ﬁlter cases are made of plastic, though, it is important to make sure the heating element does not touch the plastic, which could melt a hole and cause leaks.
A few species of aquatic turtles do not require any lighting in their tanks they prefer dark or dimly lit areas. The Matamata, for instance, favors still, murky waters in shady areas, where visibility is poor and sunlight rarely penetrates. These turtles get most of their calcium and vitamin D from their prey, rather than through exposure to sunlight.
Other aquatic turtles, however, require ultraviolet light to properly synthesize vitamin D3, which is necessary for the metabolism of calcium to build shells and bones. This necessary light must be provided with the same sort of full-spectrum UV-B lamps that were described for terrestrial tortoises. Like terrestrial tortoises, aquatic turtles also beneﬁt greatly from small periods of exposure to unﬁltered natural sunlight.
The commercial “two-in-one” hoods, which contain both a full-spectrum ﬂuorescent lamp and an incandescent basking bulb, are useful for aquatic tanks since they use only one electrical cord and thus reduce the number of necessary electrical connections.
Keeping the aquatic turtle tank clean is extremely important. Dirty tanks with polluted water not only encourage the rapid growth of algae and other pests, but they are unhealthy for the turtles and for you since they provide perfect breeding grounds for the salmonella organism (see chapter 6 for more on salmonella).
Keeping a turtle tank clean is a challenge that is complicated by the biology of the animals. Aquatic turtles do not excrete on land, and will only void their feces into the water area of their aquarium. Most of the feces is water-soluble urea and ammonia, so cannot simply be scooped out. In addition, if soil or some other substrate is used for the land area of the tank, it will stick to the turtle’s shell and feet and will be dragged into the water. Finally, when the turtles are fed in their tank, small bits of uneaten food will remain and decay, releasing toxins and fouling the water.
For these reasons, the water in the turtle tank must be cleaned continuously using powerful ﬁlters to clarify and purify the water. A number of such ﬁlters are widely available in aquarium supply shops, but most of these have been designed with the needs of ﬁsh keepers in mind, not turtle hobbyists. You must therefore be very careful in choosing a ﬁlter for your tank.
The most suitable ﬁlter for a turtle tank is the power ﬁlter, which hangs on the outside of the aquarium and uses an electric motor to pull water into the ﬁlter through a long plastic intake tube. After passing through a layer of glass wool and activated charcoal (which cleans and puriﬁes the water), the siphoned water is then returned to the tank through a trough or a plastic outlet.
This kind of ﬁlter is available in a variety of sizes for different size tanks. The manufacturers produce lists that specify which size ﬁlter is suitable for which size tank. However, the lists are calculated on the assumption that the aquarium will contain ﬁsh. Turtles, simply put, are much bigger and much dirtier than ﬁsh, and require substantially more ﬁltering power. If you have one or two turtles in your tank, you should select the size ﬁlter that is recommended for a tank two sizes larger than yours. In other words, if you have a 10-gallon tank, use a ﬁlter that is designed for a 20-gallon tank. If you have a larger tank with more turtles, get the largest capacity ﬁlter you can. If your tank is very large more than 55 gallons you may need to buy two ﬁlters and run them both at the same time.
Although such large ﬁlters can be rather expensive, turtles kept in clean water are much healthier. Plus, the reduced risk of salmonella for you more than makes up for this initial expense.
Outdoor Turtle Pond
Large colonies of aquatic turtles can be kept outside in an artiﬁcial pond a strategy best suited to areas with warm weather year-round. The basic setup for an aquatic turtle pen is the same as that already described for terrestrial tortoises. You will need to fence or wall in a large outdoor area with a variety of naturally occurring temperatures, including areas of shade and sun. The walls should be as high as practical and should be sunk into the ground to discourage burrowing (however, aquatic turtles are not as proﬁcient diggers as their terrestrial cousins).
The water pond for a colony of aquatic turtles must, of course, be much more extensive than that in the outdoor tortoise pen. A complete artiﬁcial pond, with the appropriate vegetation and basking spots, can be installed anywhere there is sufﬁcient room. Dig out an area the size and depth that you want the ﬁnished pond to be. A good pond should be a minimum of 10 feet across, with no rocks or other protruding objects left at the bottom of the hole. The center of the pond should be at least 2 feet deep so it won’t freeze solid in the winter.
Once you have excavated a suitable hole, line it with a strong waterproof material, such as butyl rubber, as thick as practical to prevent tears. This serves the same function as a swimming pool liner: It prevents leaks, keeps the dirt out of the water, and keeps the pond water from draining away. The liner should overlap the edges of the pond by about a foot, with the overlapping edge covered over by several inches of rocks and soil to hold it ﬁrmly in place.
Next, ﬁll the interior of the liner with 4 or 5 inches of clean sand, to push the liner ﬂat against the bottom and protect it from rocks, branches, turtle claws, and other potential sources of puncture. Once the liner is ﬁrmly in place, add enough water to ﬁll the pond.
If the pond is large enough at least 10 feet by 10 feet and contains a number of aquatic plants, a natural ﬁltration cycle will be established, in which the turtle waste is used by the plants as fertilizer and the plants, in turn, will oxygenate the water. This system removes the necessity for ﬁlters or water changes, although the pond may need to be topped up with water during dry periods.
You should plant shallow areas near the shore of a permanent pond with cattails, pickerelweed, and other aquatic plants that provide cover for young turtles and attract insect life to the pond. The turtles can use a number of ﬂat rocks scattered along the shore as entry and exit ramps and as basking spots. Another good idea is to place a large tree branch or trunk in the pond, so it forms a long basking platform that can be reached from either land or water. Most aquatic turtles prefer to bask on logs or branches that extend out into the water so they can dive to safety at the ﬁrst hint of danger.
The area around the pond should be open and sunny for basking most of the day, with plants and small bushes placed at the margins to provide some shade. Large trees should be avoided, as they shed leaves that would build up in and around the pond.