1- preheat oven to 350*
2-lightly spray 9 by 13 in baking dish with nonfat cooking spray.
3-cut fusih into individual peices.
4-Arrange onions on bottom of baking dishand place fish on top.
5-combine mayonnaise, garlic powder, worcestershire sauce, parmesan cheese and lemon juicein a small bowl until well blended.
6-spread mixture over fish and bake in oven for 35-40 minutes.