You can use any other white fish such as cod or flounder.
When buying the fish, ask your fishmonger to gut and scale it for you. Also ask him to remove the head and tail.
I wrapped the fish papillote-style. The exact term used is called "en papillote". The material generally used is parchment paper but you could also use aluminum foil. Make sure to use heavy duty aluminum foil to prevent the sheets from tearing too easily.