Most of the animals which lives in salt water cannot live in fresh. Some sort of small tortoise can live in fresh water also but present rule may not permit you to kee[ it under your custody which should be clarified.
Basically any type of brackish water fish can survive in fresh or saltwater. You would have to slowly ease them into the freshwater though with a holding tank with salinty that keeps dropping. Sometimes a fish store will help you with this if you do not have a holding tank to accomplish this task.