So, I have a 20 gallon tall aquarium and I would like to get 1 turtle for it. I know that pretty much ANY turtle will eventually outgrow this tank (inch of shell 10 gallons rule). And I know that a LONG tank would be better. But what kind of turtle could live in this tank until I upgrade to a larger tank? It HAS to be something that I could EASILY find at stores.Also, What Size tank would a MALE Red Eared Slider need? (I know that males are smaller). THANKS FOR THE HELP