Red-eared sliders (Trachemys scripta elegans) are medium-size turtles popular for beginner keepers because of their social personalities and hardy nature. They're tolerant of water temperature, pH and hardness fluctuations and are commonly housed in large indoor aquariums or outdoor ponds. These turtles can be housed with other turtles of their own species and with other similar species, such as map turtles, painted turtles and cooters.
Red-ear sliders can grow to 10 inches long, so you'll need a large enclosure for one adult, much more for multiples. The length of the enclosure needs to be at least 4 to 5 times the length of the turtle, and the width should be at least 2 to 3 times the turtle’s length. The depth of the water should be at least 1.5 to 2 times the length of the turtle. If you have multiple sliders, you’ll want to take into account the combined length of all the sliders. One small slider who's about 5 inches long can live in a 30-gallon to 50-gallon aquarium with land and sufficient water area One large adult should have an aquarium of at least 75 gallons, and multiple sliders will need an even larger enclosure, which is why outdoor ponds are ideal for housing groups of sliders.
When housing multiple red-eared sliders together, consider the genders of the turtles. Male sliders can be territorial toward other males; so when you house multiple males together, provide multiple basking places and caves. When housing one adult male and one adult female, the male may harass, nip and stress the female during mating season; in some cases, depending on the male's persistence, a female may become aggressive toward the male. When housing males and females together, it's important to have at least two to three females per one male so he can share the love so no one slider becomes overly stressed or injured.
Determine the Gender
It's hard to tell the gender of a slider until it is at least 4 to 5 inches long, which may be when the creature's 2 to 5 years old. The male red-eared slider has longer front claws, and the cloaca is further away from the body. The female red-eared slider has shorter front claws, and the cloaca is close to the body.
Size of the Slider
When housing multiple red-eared sliders in the same habitat, it's best to keep similarly sized turtles together. Larger turtles may bully smaller ones, and they will eat the food before smaller turtles can dine. You may notice bites or scratches on a bullied turtle. In some cases, you never see physical signs of bullying, but you may notice small sliders eating, basking and maintaining normal behaviors but failing to grow; meanwhile, overall health will decline.
As long as the enclosure is large enough, you can house a red-eared slider with other species who share the same housing requirements. But a red-eared slider may outcompete and outgrow the other species. Red-eared sliders are active, large and strong. They are much more driven than painted turtles, map turtles and cooters, which have the same housing requirements. If you want to house multiple species, it's best to house them in a large outdoor environment.