Greens do best with a semiaquatic setup. If you can, I'd take a 20 gallon (or larger) and divide it in half (you can use a tupperware container for the water side). These snakes really enjoy having a lot of aquatic vegetation in their water so stick some plastic plants in and around the water container. For bedding I'd use thick cypress mulch and moisten the surface every now and then. Provide a 60 watt basking lamp, maybe a hiding log, and feed them fish. Good luck with him. Greens are a really cool species. The few Florida Greens I've caught were HUGE! Post pics if you get him.