Turtles are not novelty pets, and if you don't have the facilities or time to care for a turtle properly, you shouldn't get one. Aside from the issues of turtles being taken from the wild and the risk of salmonella, most turtles get large. That tiny baby turtle might initially fit inside a small fish tank. But if it survives, it will need a much bigger tank or an outside pond within a year or less. However, a few species do remain small enough to live inside a large tank their entire lives, with the very smallest reaching a maximum size of about 4 inches.
Small Species of Turtle
Among the small turtles often kept in captivity are several species of mud and musk turtle, the red-eared slider and the diamondback terrapin. Depending on the species, adult musk turtles may reach no more than 4 to 6 inches long. The smallest species of mud turtle is about 5 inches long. Red-eared sliders are common in the pet trade and although they aren't large, they're not that small, either. Adult sliders grow to a foot long. Female diamondback terrapins can grow to 9 inches, but the males are about a third smaller.
As a very rough guide, each inch of turtle needs 10 gallons of tank or pond space. For example a red-eared slider, which will grow to about 12 inches long, needs a 120-gallon or larger tank. The needs of each species vary. Some turtles need plenty of landing areas, heaters or, in the case of terrestrial tortoises, soil to burrow in. Outdoor ponds are a good option if the climate is suitable for your turtle and the pond is well-secured against predators and against turtles escaping.
The exotic pet trade has a dark side, which includes those cute little turtles. Pet traders regularly take turtles from the wild, which in some cases threatens the survival of the species, such as the alligator snapping turtle and Chinese box turtle. Then there is the issue of tiny turtles passing salmonella on to humans. Turtles are not a good pet for small children anyway; they are not friendly to people and they require a great deal of care. Because of the risk of infection, it is now illegal to sell turtles smaller than 4 inches in the United States. People sometimes release unwanted turtles that have grown too big "into the wild" which, if the turtle survives, can be bad news for native species.
Before purchasing a turtle, check the species, that the animal is captive-bred and it is legal to keep such turtles in your area. Because many people buy small turtles without realising the commitment and care they need, there are a lot of unwanted turtles needing homes. The best place to get a turtle is a reptile rescue sanctuary rather than a pet store. Such places can also advise you on the needs of the turtle, and they also know what species the turtle belongs to. Failing this, go to a reputable breeder.