Hearty Crockpot Fish Stew

Name: Hearty Crockpot Fish Stew
Ingredients: 1 1/2 pounds catfish (cut into 2-inch pieces; haddock or flounder fillets are also acceptable); 2 tablespoons butter (melted, or extra-virgin olive oil); 1 large clove garlic (minced); 1 large onion (sliced); 1 green bell pepper (seeded and cut in 1-inch pieces); 1 to 2 small zucchini squash (sliced); 1 (14.5-ounce) can whole tomatoes; 1/2 teaspoon dried leaf basil; 1/2 teaspoon dried leaf oregano; 1 teaspoon salt; 1/8 teaspoon pepper; 1/4 cup dry white wine; Optional: 4 ounces mushrooms (sliced); Garnish: parsley