Preheat oven to 425 degrees. Place fish in an 11 x 7 inch baking dish coated with cooking spray. Combine lime juice, mayonnaise, onion powder, and pepper in a small bowl; spread over fish. Sprinkle with breadcrumbs; drizzle with butter. Bake at 425 degrees for 20 minutes or until fish flakes easily when tested with a fork. Sprinkle with parsley.