Thaw fish, if frozen. Cut the fish into 6 serving-size pieces. Spray a 2-quart rectangular baking dish with nonstick cooking spray. Place fish in the prepared baking dish, tucking under any thin edges so fish cooks evenly. Measure the thickness of the fish. Sprinkle the fish with the lemon-pepper seasoning.
Bake fish, uncovered, in a 450 degree F oven until fish just flakes easily with a fork (allow 6 to 9 minutes per 1/2-inch thickness). Drain off any liquid.
Meanwhile, cook fettuccine according to the package directions. In a medium saucepan cook mushrooms, green sweet pepper, and onion in the 1/4 cup water, covered, about 5 minutes or until tender. Drain; add pizza sauce. Heat through.
Serve fish on fettuccine; spoon sauce over fish. Sprinkle with cheese. Makes 6 servings.