Creamy Norwegian Fish Soup

Name: Creamy Norwegian Fish Soup
Ingredients: 2 1⁄2 tablespoons butter; 2 1⁄2 tablespoons plain flour; 4 -5 cups fish stock or 4 cups vegetable stock; 1 medium carrot, finely chopped in strips; 1 -2 cup leek, finely chopped in strips; 1 -2 potato, peeled and cut into small cubes (optional); 1 (14 ounce) can chopped tomatoes (optional); 12 peeled raw shrimp (approx); 12 mussels (approx) or 12 small scallops (approx); 4 -6 ounces catfish (or fish of your own choice); 1⁄2 cup heavy cream; 1⁄4 cup chopped fresh parsley; salt and pepper; 2 tablespoons sour cream (optional); 2 teaspoons lumpfish caviar (optional)