Yellow-bellied sliders are semi-aquatic turtles that are native to the southeastern United States, including South Carolina. They are generally hardy reptiles that can tolerate a wide range of climates. However, yellow-bellied sliders are generally not recommended for outdoor ponds in South Carolina during the winter, as the temperatures can drop too low for them to survive.
Yellow-bellied sliders can survive in water temperatures as low as 50 degrees Fahrenheit, but they become inactive and stop eating when the water temperature drops below 60 degrees Fahrenheit. If the water temperature drops below 45 degrees Fahrenheit, yellow-bellied sliders can go into brumation, a state of dormancy similar to hibernation. During brumation, yellow-bellied sliders' heart rate and respiration slow down, and they stop eating and drinking.
However, if the water temperature drops below 32 degrees Fahrenheit, yellow-bellied sliders can freeze to death.
Therefore, while it is possible for yellow-bellied sliders to survive in a koi fish pond outdoors in South Carolina during the winter, it is not recommended, as the temperatures can drop too low and they may die.