1. Heat oil in a large Dutch oven over medium heat. Add onion and bell pepper; cook 5 minutes. Add wine and next 6 ingredients; bring to a boil. Reduce heat; simmer 5 minutes, stirring occasionally.
2. Nestle fish into tomato mixture; top with mussels. Cover and cook 8 minutes; gently shake pan twice to stir mussels (do not lift lid). Discard bay leaf and any unopened shells. Sprinkle with parsley.