What age can I start teaching my puppy to swim in the bathtub?

With a name like Prince Sidon, it sounds like you are really gearing up for the water! It really is going to depend on your dog's breed, and if he even likes the water (hopefully he will like it as much as the Zora he's named after!). I would wait until Sidon is a few months old before going too crazy on playing in the water, and make sure he is up to date on all his vaccines before exploring any public places. A shallow kid's pool can be used with a small amount of water to help encourage him to play in it, and offering treats and praise when he explores the water can help. Tossing a favorite toy into the water can also encourage playing and exploration.

Most dogs are natural swimmers on their own, and spending time going to places with water can help encourage this behavior. Just make sure you are practicing water safety like you would with a child or adult human - including using a life jacket if you are on a boat, etc, as even the strongest swimmer can still get exhausted or swept up by currents.