Whisk together mayonnaise and next 4 ingredients. Spoon 1/2 cup mayonnaise mixture into a shallow bowl or pie plate. Cover and chill remaining mayonnaise mixture.
Stir together cereal, garlic powder, and salt until blended.
Dip fish into 1/2 cup mayonnaise mixture in pie plate, coating both sides; dredge in cereal mixture. Place fish on a lightly greased wire rack in a jelly-roll pan.
Bake at 450° for 14 to 15 minutes or until fish flakes with a fork. Serve with remaining mayonnaise mixture and lemon wedges.