Heat quarter cup olive oil in Dutch oven or large heavy pan over medium heat. Add onions and saute 1 minute without browning. Add carrot, green pepper, leek, celery and fennel and saute 5 minutes. Stir in crushed tomatoes, tomato paste, water, salt, pepper, basil, oregano, thyme, bay leaves and cayenne pepper. Partially cover and simmer over low heat 2 hours, stirring occasionally. (Sauce can be covered and kept warm over low heat for several hours longer. Stir occasionally.) Remove bay leaves.
Heat remaining quarter cup oil in a large skillet over high heat. Add garlic and cook 5 seconds. Immediately add fish, shrimp and scallops. Saute until just cooked through, 2-4 minutes. Add seafood to sauce and stir gently.
Pour wine into skillet and cook 30 seconds over medium heat, stirring up any loose bits. Add clams to skillet. Cover and cook until clams open, 2-6 minutes. Transfer clams as they open to sauce. Discard any that do not open. Gently stir shrimp and crab meat into sauce. Cover and cook cioppino until all seafood is hot, 2-3 minutes longer.
Ladle cioppino into large casserole or soup tureen or directly into shallow soup plates. Garnish with chopped italian Parsley.