Place fish fillets in a bowl, sprinkle with salt, turmeric, cumin, black pepper and garlic, tossing to coat well. Cover and marinate for 20 minutes at room temperature or longer in the refrigerator. Preheat oven to 400F degrees. Coat the bottom of baking dish with the oil. Place the fish in a single layer and pour the marinade over it. Bake uncovered for 20-25 minutes. The fish should be firm to the touch. Fish is done when it easily flakes with a fork. Sprinkle with lemon juice.