It is not recommended that you freeze fish stew as the fish will become very soggy. You can, however, freeze the cooked stew (before adding the fish and shrimp). This works great if your seafood is frozen too! Transfer the cooled stew to an airtight container and freeze up to 3 months. When you are ready to make it, thaw the soup and the fish in the refrigerator. Add the soup to a slow cooker on high until hot. Add the thawed seafood and cook 30 minutes or until the fish flakes easily.