River cooters are a native group of turtles found in rivers of the Eastern U.S. According to the “Field Guide to Reptiles and Amphibians of the Eastern and Central North America” by Roger Conant and Joseph Collins, four species or subspecies of river cooters exist: the Eastern River Cooter (Pseudemys concinna concinna), Suwannee River Cooter (Pseudemys concinna suwanniensis), Hieroglyphic River Cooter (Pseudemys concinna hieroglyphica) and Texas River Cooter (Pseudemys texana). Reptile hobbyists frequently keep these popular turtles as pets in aquatic or semi-aquatic terrariums.
Although mainly herbivorous, river cooters do eat some animals in their diet. In the wild, they prefer feeding on freshwater aquatic plants, such as eelgrass (Vallisneria Americana), elodea (Elodea canadensis), Carolina fanwort (Cabomba caroliniana), hydrilla (Hydrilla verticilata) and various algae. Both adults and juveniles include aquatic animals–-snails, crayfish, small fish, tadpoles and numerous small insects–in their diet, but juveniles require proportionally more protein and are more omnivorous than adults. Despite their name, river cooters occasionally inhabit salt- or brackish-water habitats, where they feed mostly on turtle grass (Thalassia testudinum).
Captive Food: Plants
River cooters are primarily vegetarian and will consume a variety of garden vegetables in captivity. Turnip greens, mustard greens, collard greens, spinach, dandelion, zucchini and carrots are all suitable foods. Native and introduced aquatic plants–-such as duckweed, eelgrass (Vallisneria Americana), elodea (Elodea canadensis), Carolina fanwort (Cabomba caroliniana), water lettuce (Pistia stratiotes), water hyacinth (Eichhoria crassipes) and hydrilla (Hydrilla verticilata)–can also be fed to pet river cooters. Be sure to offer your pet turtle a diverse diet by mixing and rotating among these easy to find foods, as this is the best way to ensure a balanced diet.
Captive Food: Animals
While primarily vegetarian, a complete diet must include some animal material. Rapidly growing hatchlings and juveniles require more protein than adults, but they should still receive no more than about 35 percent of their diet in prey items. Convenient prey items include insects (e.g., crickets), worms, guppies and crayfish, which can often be purchased at bait shops or grocery stores.
A number of the commercially prepared turtle diets make excellent river cooter food. The key is to make sure the commercial brand you choose is designed specifically for river cooters or that it is designed primarily for vegetarian turtles. Commercially available low-protein diets designed for goldfish or koi can also be used, if used as a part of a varied diet.
Vitamins and Supplements
Turtles must receive enough calcium and vitamin D3 in their diet to maintain proper shell growth, or they will suffer from metabolic bone disease. Sprinkle a powdered calcium supplement, such as Repti-Cal, on the turtle’s food before all feedings. According to Chelonia.org, you should use a calcium supplement that contains vitamin D3 if you keep your turtle indoors (under artificial light). You can give turtles housed outdoors (under natural sunlight) a calcium supplement without vitamin D3. The reason for the difference is that turtles physiologically produce vitamin D3 in the presence of sunlight, whereas they do not under most artificial light sources. Vitamin D3 is required to process and incorporate calcium into bone tissues. Cuttlefish bones are available commercially and provide an additional source of calcium that your pet turtle can choose to gnaw on when it wants to.