1 tablespoon olive oil  | 
                                                2 garlic cloves, sliced  | 
                                                2 1/2 cups slivered onion  | 
                                                1/2 teaspoon salt, divided  | 
                                                2 cups chopped peeled plum tomato (about 4 tomatoes)  | 
                                                1 3/4 cups thinly sliced fennel bulb (about 1 small bulb)  | 
                                                1 cup dry white wine  | 
                                                1/3 cup chopped fresh basil  | 
                                                1/4 cup chopped pitted kalamata olives  | 
                                                1 tablespoon tomato paste  | 
                                                1/8 teaspoon crushed red pepper  | 
                                                2 teaspoons capers  | 
                                                1 bay leaf  | 
                                                1/2 cup water  | 
                                                1/8 teaspoon black pepper  | 
                                                6 (6-ounce) halibut or cod fillets  |