I personally would look into some smaller sharks that can be kept for life in your pond. The bamboo, bullhead and marbled cat sharks pictured here would be much more papropriately sized, although maybe not the look your going for, I think it will look much better to have a few of these full grown swimming around then one full grown shark barely moving of the types you listed (wich is a possibility, there's no gaurantee somone is gonna take in an overgrown shark from you, not to mention how are your gonna move one)...