For every 1 inch of thickness, baking time is 10 minutes. Add five minutes to the cooking time if the fish is wrapped in foil. For example, a fish that measures 2 inches will cook for 25 minutes when wrapped in foil. Place the fish on a piece of heavy-duty foil, large enough to have extra room to fold and seal.or every 1 inch, the grilling time should be 10 minutes. Add five minutes for fish cooking in foil. For example, the cooking time for a fish that measures 2 inches will be 25 minutes when it is wrapped in foil. Place the fish on a piece of aluminum foil large enough to fold and seal.