Preheat the oven to 375 degrees. Use about 1 teaspoon of the oil to lightly oil a rectangular or oval oven dish large enough to hold the fish.
Combine the olives, parsley, and garlic. If using a whole fish, put half the mixture inside the fish, set the fish in the oiled dish, and strew the remainder of the olive mixture over the top. If using fish steaks or fillets, arrange in the dish and strew the olive mixture over the top.
Sprinkle the fish with salt and pepper and pour on the remaining olive oil and the lemon juice. Place in the preheated oven and bake for 30 minutes, basting every 10 minutes with the pan juices.
When the fish is done, remove from the oven and serve immediately, garnished with finely minced parsley mixed with the grated rind of the lemon. Yields 6 servings.