Cut the fish fillets into 3-inch pieces. Season with 1 tablespoon of the rub. Set aside in the refrigerator. Make a roux by combining the oil and flour in a large cast-iron or enameled cast-iron Dutch oven over medium heat. Stir slowly with a wire whisk or wooden spoon for about 15 to 20 minutes, or until the roux becomes dark brown, the color of chocolate. Add the celery, onions, bell peppers, and chilies. Cook, stirring often, for 6 to 7 minutes. Add the bay leaves and garlic and cook for about 2 minutes. Add the tomatoes, water, and the remaining 1 teaspoon rub. Reduce the heat to medium-low and cook, uncovered, for about 1 hour, or until a thin oil film appears on the surface. Stir occasionally to prevent the mixture from sticking. Increase the heat to medium, add the broth, salt, and cayenne and cook for about 15 minutes. Lay the fish in the mixture and cook for 10 to 15 minutes, or until the fish flakes easily with a fork. During the last 5 minutes of cooking time, add the green onions and parsley. Remove the bay leaves. Serve hot.