In a Dutch oven cook onion, celery, carrot, and garlic in hot oil over medium-high heat about 5 minutes or until tender. Add broth and tomatoes. Heat to boiling; reduce heat. Simmer, covered, for 15 minutes. Stir in fish. Simmer, covered, about 5 minutes more or until fish begins to flake when tested with a fork. Stir in parsley.