Now that I've studied Tank a little more, I guess there's a pretty good chance he's a "she". I don't know if you can see the concavity of the plastron from the pictures. It's not the deepest I've seen. But the back end doesn't flare out and the tail isn't all that large. Between the slightly tapered waist and the concavity, as well as behavior, I really thought it was a "He.". Guess I'll watch for eggsIf you post a pic of Tank's plastron and we can all give an educated guess.