Proper cooking time for fish depends on the type of fish and the cooking method. All fish and seafood must be cooked to an internal temperature of 145 F regardless of the cooking method to prevent foodborne illness, says the United States Department of Agriculture.
Fish can be baked, broiled, grilled or poached in an oven preheated to 400 or 450 F. Temperatures vary for fish cooked on a stove top, on an outdoor grill or in a microwave oven. Generally speaking, cook fish for 10 minutes per inch of thickness. Salmon or swordfish, which typically measure approximately 1-inch thick, can be cooked for 10 minutes. A thin piece of fish, such as tilapia, can be cooked for 5 minutes or less. Use a food thermometer to ensure the fish is done before serving.