Place onion, green capsicum, garlic, tomatoes, chicken stock, tomato sauce, mushrooms, olives, orange juice, wine, bay leaves, dried basil, fennel seeds and pepper into a slow cooker. Cover and cook on low 4 to 4 1/2 hours or until vegetables are crisp tender.
Stir in prawns and cod. Cover. Cook 15 to 30 minutes or until prawns are opaque. Remove and discard bay leaves. Serve.