My smooth doggies do the exact same thing. It is the one trait that makes them the most difficult to care for. Even at the aquarium they would tail walk and leap out of just about any tank. Other than that they are very hardy and do well in captivity. I, too, have heard mixed info about leopard sharks. One retailer assures me that his are legal while another says it is illegal to sale any leopard under three feet. I haven't been able to verify anything just yet and have sent an email off to the NMF to find out. I'll let you all know. I reason I mention this is because a couple years ago I almost got involved with a guy trying to sale brown sharks that were illegal sized ( w/o special permitting can't possess any under 54 inches), I found out that if I was to have bought them I would have been in as much trouble as the guy selling them. Just a warning, make sure you know the regs!