Lightly grease a 13- x 9- x 2- inch baking dish. Arrange 6 fillets on bottom. Evenly spoon green olives on each fillet; top with remaining fillets, securing each fillet "sandwich" with wooden picks. Brush surface of fish with olive oil, and sprinkle with salt and pepper. Garnish with chopped ripe olives.
Bake, uncovered, at 375° for 25 minutes or until fish flakes easily when tested with a fork. Transfer to a warm serving platter. Remove wooden picks; garnish with tomato wedges and parsley. Serve immediately.