Starting Out with Semi-Aquatic Turtles

David T. Kirkpatrick, Ph.D


Twenty years ago, the federal government passed a law banning the sale of turtles with a carapace length of less than four inches. Although designed to prevent people from contracting salmonella poisoning, the ban probably saved untold thousands of baby red-eared slider turtles from an untimely death. The state-of-the-art turtle container at that time consisted of a foot-wide plastic bowl with a small island in the center, on which stood a brown and green plastic palm tree. A healthy, well-fed red-eared slider hatchling would have outgrown it within two months. However, at that time the food sold for turtles consisted of dried ants and ant larvae. If kept at room temperature (as they usually were) and fed only dried ants, not even the very hardy red-eared slider usually survives.

Thankfully, turtle care has progressed in the last two decades. Many different types of aquatic turtles can be raised, maintained and bred when provided with the appropriate environment. The most common way to keep water turtles in captivity is in a glass aquarium. If you intend your turtle set-up to be a display piece, a well-designed aquarium arrangement will show off your turtles beautifully. However, very functional habitats can be constructed out of large plastic tubs, from utility sinks, or even metal cattle troughs, as long as the set-up meets a few basic requirements. This article will discuss those requirements and give a few tips for successful turtle-keeping.

Selection of an appropriately-sized tank is one of the most important elements in successful turtle-keeping. The aquarium must be large enough to give the turtle adequate swimming room in both length and depth. I consider a 20 gallon aquarium to be a minimum size, but bigger is always better. Only juvenile turtles should be kept in smaller aquariums, and they will outgrow them, so you might as well start with a bigger tank and save yourself money! So-called "long" or "breeder" tanks are usually better investments than "high" aquariums, as they provide a larger surface area for your animals. The water level should be deeper than the turtle is wide - if the water is shallower and the turtle manages to land upside-down in the water it may not be able to flip back over and will drown. Also there should be no place underwater in the tank where the turtle could get wedged in such a way that it cannot get to the surface to breathe. So, for these reasons and for the happiness of the turtle, larger aquariums are definitely better.

The aquarium does not need to have decorations, nor does it require sand or gravel on the bottom. These actually make it more difficult to clean and are not necessary for the turtle. Many turtles will eat any water plants that are placed in their enclosure. However, one necessity is an area that is totally out of the water on which the turtle can haul out and dry off. Worn driftwood, cork bark floats, or smooth flat rocks work well, as they are not likely to rub or scratch a turtle's shell as it climbs out of the water. Position a spotlight over the rock or wood to simulate the sun, allowing the turtle to bask. (Take care not to put the aquarium in full direct sunlight however - if the turtle cannot get out of the sun, you may end up with a baked dead turtle.) Most turtles do very well with this minimal set-up: a large, deep undecorated aquarium with a spotlight over a flat rock out of the water on which they can dry off and sun themselves.

A land area makes the aquarium look more attractive and is quite functional in addition. It is an absolute requirement if you intend to breed your turtles, as they will need an area in which to bury their eggs. With no access to a land area, a female turtle will retain her eggs as long as possible and then drop them into the water or on her basking area. Retaining eggs for too long can injure a turtle - for example, an egg might rupture while still inside the female, leading to a massive infection.

The size and depth of the land area is determined by the type of turtle - larger turtles will need a deeper area than smaller turtles to bury eggs. Also, some turtles are more terrestrial than others, and so benefit from a large land area. To make a land area, glue pieces of clear plastic into place with silicone aquarium sealant. For example, one end of the tank can be walled off with a vertical or diagonal piece of plastic (see photo). More intricate arrangements are also possible. As an example, three pieces of plastic can be glued into a "U" shape in the middle of the aquarium. This set-up lets the turtles pass underneath, allowing them to move from one end of the tank to the other without going up onto the land area. Note that plastics are flexible; when glued to glass it is possible they will separate due to flexing if they are not supported or if the plastic is not thick enough. For example, in this enclosure, the edge of a brick supports the horizontal piece of plastic, whereas the thickness of the plastic is sufficient in this setup.

A fully submersible water heater helps keep the water at a reasonable temperature year-round, as many water turtles prefer water temperatures that are above ambient room temperature. However, the temperature of the water will depend on the type of turtle that you keep, and therefore you should investigate the natural environment of your turtle, if you are not sure of its requirements. Most underwater heaters attach to the side of an aquarium with suction cups. If your turtle is very active, it may become necessary to wall off the heater to some degree to prevent the turtle from breaking it. Also, buy an aquarium thermometer. Many heaters are not accurate and require monitoring to assure that the desired temperature is maintained.

A filter of some type can also be quite useful. I prefer the fully submersible type that do not require an air pump, but are self-contained units, sucking water in through the bottom, passing it through a sponge filter, and expelling it out the top. For larger aquariums canister filters are a good investment. Although their initial cost can be high, the time saved in water and filter changes makes them well worth the money. Many different models are available, from a number of different manufacturers. As with aquariums, larger is usually better. The greater the volume of water moved and the larger the filtering surface, the cleaner the water will remain. This will reduce the frequency of water changes required. Undergravel filters can be used, but often become clogged too quickly due to the large amount of waste material that turtles are capable of producing.

A final item that might be beneficial is a fluorescent hood with a full-spectrum light bulb, such as a VitaliteTM. There is considerable debate as to the effectiveness of fluorescent full-spectrum lights in providing enough ultra-violet radiation of the correct frequency to stimulate production of the Vitamin D3 necessary for proper calcium utilization. In my experience, hatchlings raised on a balanced diet with calcium and vitamin supplements do not require full-spectrum lighting or additional UV radiation. However, a full-spectrum light does deliver a more natural type of light, and this may have a beneficial psychological effect on your turtles. A fluorescent lamp should not be used as a replacement for a spotlight, as the fluorescent tube does not get warm enough to be a proper basking light.

For convenience, the light or lights over your turtle tank can be controlled using an ordinary timing device to turn them on in the morning and off in the evening. The timer should be adjusted periodically to reflect the changing length of the day. This lengthening and shortening of the photoperiod signals the passing of the seasons and can act as a stimulus for mating, if you are keeping multiple turtles with the intention of breeding them.

The set-up for your turtle should be completed and functioning before acquiring a turtle. This allows time to monitor for problems in filters, heaters or in the arrangement of the tank. It is a lot harder to patch a leaking land area when the tank is full of turtles! Having the enclosure up and running also places less stress on the newly arrived turtle, allowing it to adjust more quickly to its new environment.

Choosing an appropriate turtle is very important. Final size of the turtle is often a major factor in deciding which turtle to keep. A number of the more commonly available turtles can grow to a large size. Sliders may reach a foot or longer in size, depending on the specific species, while snapping turtles can get even larger. Do not buy a turtle just because it looks interesting - find out what type of turtle it is, read up on it, and decide if you can provide it with a good home. A number of good books on turtles have been published within the last few years. The most comprehensive is Carl Ernst and Roger Barbour's "Turtles of the World". More recently they, along with Jeffrey Lovich, wrote "Turtles of the United States and Canada". However, both of these books are oriented towards the natural history of the turtle. If you are interested in captive maintenance of turtles, read Philippe de Vosjoli's "The General Care and Maintenance of Red-Eared Sliders and Other Popular Freshwater Turtles". (For a more complete overview of commonly available semi-aquatic turtles, click here.)

My personal favorites among the turtles are the mud and musk turtles (Kinosternon and Sternotherus species). Another good animal is the Reeve's turtle, Chinemys reevesii. Individuals in these species stay rather small, usually under six inches. The painted turtles, cooters and sliders are attractive and easy to keep if you can give them enough room. Adult females of some species can grow to be 16 inches in length; males tend to be smaller than females. Finally, a turtle that is just about indestructible is the common snapper but, like the sliders and painted turtles, will require a large amount of room. Eventually it will outgrow most aquariums (for a more detailed overview of snappers and their care, see Richard Bartlett's article in the January 1995 issue of Reptiles). More exotic aquatic turtles are available occasionally through reptile dealers.

Food for turtles varies widely, depending on the type of turtle that is being kept. Some turtles are mainly carnivorous, while others are omnivorous and will eat just about anything you give them. Basically, it pays to determine the food requirements of the type of turtle you want to keep. Some common items are various types of lettuces such as Romaine or Red-leaf (avoid Iceberg), collard greens, or finely chopped mixed vegetables. Many turtles will eagerly consume earthworms, small feeder guppies, raw beef heart, cooked chicken or a low-fat dog food. A number of commercial products are available, such as Tetra's ReptoMin, Wardley's Reptile Ten, and Purina's Trout Chow. I have successfully raised hatchlings of a number of species on a diet of ReptoMin and Reptile Ten, with an occasional earthworm as a treat. Above all, remember to provide a varied diet. Do not allow your turtles to fixate on one particular food item to the exclusion of all others.

If a well-balanced diet is provided, most turtles, especially adults, will not require a lot of additional vitamin supplementation. However, rapidly growing hatchlings and females producing eggs can benefit from extra vitamins and calcium. One easy means of providing more calcium is in the form of a calcium block. Calcium carbonate, in the form of Plaster of Paris, is mixed with water, poured into molds, and allowed to solidify. A vitamin powder can be added while the Plaster of Paris is still liquid. Art supply stores are a good source of Plaster of Paris. Before purchasing it, check the ingredients list to verify that no anti-fungal compounds have been added.

Adult turtles do not require daily feeding. Once every second or third day, they should be fed as much as they will eat in a few minutes. Do not overfeed your turtles. Turtles will over-eat and become fat, with the same consequences to their health as with any other overweight animal. Fat turtles can be recognized by their inability to retract their head and legs fully, or at least not all at the same time. Hatchlings and small juveniles can be fed daily until their growth rate begins to slow down.

I recommend that you feed your animals in a separate container (plastic tubs or deep trays work well) as turtles can be rather messy eaters. Broken up food bits will quickly foul the water if you feed turtles in their aquarium, forcing a water change every couple of days. If the turtles are fed outside the tank, and it contains a large filter, the water may remain clear for months at a time. However, the filter itself should be cleaned routinely to prevent a buildup of debris. Similarly, at least a portion (one-third to one-half) of the water volume should be replaced every few weeks. This prevents the accumulation of compounds that might be detrimental to your turtle. Infrequent water changes may also result in alterations in water pH that could affect a turtle's health.

In conclusion, water turtles can do quite well in captivity if their needs and lifestyles are taken into account. If they are provided with a good diet, clean water, light, and enough room, they will more than repay you for the moderate amount of work that it takes to maintain them successfully. But please, when acquiring a turtle, consider carefully your ability to provide it with a reasonable living environment. If you are willing to make that commitment, however, I'm confident that you will not regret it.

Bibliography:

Bartlett, Richard D. 1995. "Aquatic Nightmares: The Common and Alligator Snappers" in Reptiles, Vol. 2, No. 3. Fancy Publications, Inc., Irvine, CA.

de Vosjoli, Philippe. 1992. The General Care and Maintenance of Red-Eared Sliders and Other Popular Freshwater Turtles. Advanced Vivarium Systems, Lakeside, CA.

Ernst, Carl H. & Roger W. Barbour. 1989. Turtles of the World. Smithsonian Press, Washington, DC.

Ernst, Carl H., Jeffrey E. Lovich, & Roger W. Barbour. 1994. Turtles of the United States and Canada. Smithsonian Press, Washington, DC.


This article copyright 1995 by David T. Kirkpatrick. Originally published in Reptiles, October 1995, pages 92-105.

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