If kept captive, it is important to try to duplicate the red ear's natural habitat and diet to the greatest extent possible. Red ears require a fairly large swimming area with good water quality, a basking area that lets them get completely out of the water to dry off and get warm, proper lighting, temperature and food.
The best conditions for housing red ears can be most easily obtained in a properly setup outdoor enclosure. The turtles need a small pond that they can easily enter and exit and should have access to a land area. A secure fence or landscape timber walls will prevent escapes. The water in the pond can be filtered or simply refreshed with a hose - in any case it must be kept clean. A child's wading pool can be used to temporarily house red ears outdoors, but remember to provide some shade and a basking area.
If a red ear is to be kept in an aquarium for a short time, there should be about 5 gallons of water per inch of carapace length. Using this rule of thumb will avoid overcrowding and make the container easier to maintain. If you are not interested in viewing the turtle from the side, plastic containers such as storage boxes or cement mixing tubs can be used. The water should be maintained at 80 degrees F or above using a good aquarium heater. After the turtle reaches about 4 inches of carapace length it should be kept in an outdoor setup as described above. Females must have access to dirt in order to lay eggs.
Turtles are heavy feeders and an overloaded container will be very difficult to keep clean. Red eared turtles will shred their food as they eat it, contributing to the waste load of the tank or pond. If desired, turtles can be fed in a separate container, thus reducing the amount of food left in the their living space. Remember that aquatic turtles must be in water to be able to swallow. It is also important to use water that is the same temperature in both containers.
If the tank is not overloaded, a well established under gravel filter, driven by a power head (the standard air lift just doesn't provide enough water flow) and with 3 to 4 inches of gravel bed above it, will maintain excellent water quality. The oxygenated water flowing through the gravel bed encourages the establishment of a colony of beneficial bacteria. These bacteria then aid in the reduction of waste products. Remember that it takes a few weeks for the aerobic bacteria to become well established in the gravel bed. Once established, constant water circulation is important. The bacteria colony will die if deprived of oxygen for an extended time. An occasional partial cleaning of the gravel bed using a standard aquarium gravel cleaning siphon is required to remove any undigested waste and to prevent the filter bed from clogging. This periodic siphoning also affords an opportunity to top up the tank with fresh water and reduces the buildup of harmful materials. Large power canister filters, although expensive, also work well. The filter media in the canister filter will have to be cleaned or replaced every one or two weeks.
A red ear must be able to dry its shell occasionally to prevent fungus and bacterial attacks. This is one reason they bask in the wild. The basking area in an aquarium can be a large branch that extends out of the water or a pile of smooth rocks large enough to afford a high and dry area. Floating plastic islands and lily pads are available but they may not support the turtle sufficiently to allow it to get completely out of the water and dry out. A solid basking area is preferred. If kept in an aquarium (not recommended), a light with sufficient UV energy, such as a Vita-Lite, is essential. The light should not pass through intervening glass as the glass will remove most of the beneficial UV. The light should be within 6 inches of the basking area. An incandescent light in a clamp on reflector can be used to provide extra heat at the basking site and will be appreciated by the turtle. This extra heat source has the added benefit of providing a temperature gradient that allows the turtle to choose its preferred body temperature. For optimum health, red ears need a range of temperatures from 75 degrees F to 95 degrees F.
The best diet for a red ear is one that duplicates its natural food as closely as possible. Live foods are particularly enjoyed and beneficial. The key to success is to feed a wide variety of foods. They enjoy earthworms, snails, meal worms, crickets, grasshoppers, trout chow, catfish chow, chicken, fish, feeder (live) fish, ReptoMin, etc. Plants taken include most plants found in tropical fish tanks, duckweed, water hyacinth, arrowhead, anacharis, cabomba, hornwort, ludwigia, etc. Try freshly sprouted seeds such as alfalfa, mung beans, etc. Hornwort can be easily grown in a spare aquarium along with water snails (red ramshorn, for example) and some feeder fish. Mosquito fish (Gambusia) or guppies will readily spawn in a tank with a thick growth of hornwort. This setup can provide a fair amount of the turtle's foods. To avoid problems, feed a wide variety. Fatty foods and all red meats should be avoided. Red eared turtles, in common with most aquatic species, must be in the water in order to swallow. If properly maintained, red eared turtles are hardy and long lived. A female was still alive in June, 1992 after more than 37 and a half years in captivity! Turtles as pets are long term commitments.
After being held captive, a turtle, even a native such as the red ear is in our area, should not be released back to the wild unless checked by a competent vet or knowledgeable amateur. The animal may not be able to recognize and capture its natural prey, and it is possible to introduce unknown pathogens into a wild population through such releases. A non-native species should never be released and a native should not be released later than August so that it has a chance to acclimate itself before needing to hibernate.
If you grow tired of your turtle, try to find an interested person to take it or contact the GCTTS or your vet for a referral.