I kept one for about 6 months. Caught it at the pond across the road from my mom's house. It was about 1" across and when I let it go, it was 6". Very cool and was a visious predator. I would feed it minnows and newts I caught in the same pond and it was a treat to watch him eat. VERY messy though, so if your thinking about keeping one even for a short while, you need good filtration. A pond would be needed for sure if you were to keep long term as I have seen them around here (West Virginia) as big as 24"+ across the shell from side to side, longer front to back.