Most reptiles are solitary animals and don't need to be kept in groups for company, and keeping them together can result in fighting or injury. Turtles are different and can do well in groups if they have enough space. When deciding if two red-eared sliders should live together, there are several things to consider. The red-eared slider is usually a good turtle species to keep in groups.
Gender is an important determining factor of how red-eared sliders will behave when kept in groups. Keeping more than one male together may result in fighting, territorialism and injury or death to one or all the male turtles, especially if a female is present. If a male and female are kept together, keepers should be prepared for the inevitability of breeding and the laying of eggs. Egg laying is stressful for a female turtle and can result in death or calcium deficiencies, and a female red-eared slider can lay up to 20 eggs at once, which means 20 babies that will need homes. Alternatively, the turtle can be fed calcium supplements and the eggs can be frozen after laying so they don't develop. The best red-eared sliders that can live together in a stress-free situation would only be females.
It is easy to determine the gender of a red-eared slider. Males have extremely long front claws that can grow up to an inch in length, while females have short ones. Females also have a vent that is near where the tail meets the body, giving them the illusion of a longer tail. Males have a vent that is halfway down the tail.
Red-eared sliders are basking turtles, which means they will leave the water to find a log, rock or a floating surface to bask on. This basking lets them dry off their shells once in a while as well as to warm up, as they rely on external heat sources to regulate their own temperature. Basking turtles are usually compatible with other basking species, so red-eared sliders can live together with cooters, map turtles and painted turtles.
Red-eared sliders that live together should always be similar in size to prevent fighting or injury. Very large turtles may try to eat smaller turtles, which can also cause injury or death. Red-eared sliders of different sizes can also compete for food, with the smaller turtles being too slow and inexperienced to find adequate food and obtain proper nutrition.
Red-eared sliders need adequate space to swim around, leave the water occasionally as well as get away from other turtles. They make excellent pond turtles, because ponds provide plenty of space for multiple turtles living together. If kept in an outdoor pond, red-eared sliders can be tasty snacks for scavengers such as raccoons. A mesh net placed over the pond will prevent the turtles from being eaten.