Melt bacon fat in a large skillet over medium heat. Stir in the flour and cook until browned, stirring constantly to make a brown roux (see Editor's Note). Stir tomatoes, tomato sauce, minced onion, green pepper, parsley, garlic, water, salt and pepper into the roux. Bring sauce to a boil, then reduce heat to medium-low, and simmer for 20 minutes. Add shrimp to mixture and cook until the shrimp turn pink, and have turned opaque in the center.