In a large pot or Dutch oven, cook shallots and fennel in oil over moderate heat until translucent, about 5 minutes.
Add garlic and sauté for 2 more minutes.
Add the bay leaf, red pepper flakes, oregano, thyme, tomato paste, salt and pepper and mix well.
Add all remaining ingredients, except for the seafood and garnish, and bring to a simmer.
Cover and cook on medium-low for 30 minutes.
Season shrimp, scallops and fish pieces lightly with salt and pepper and set aside.
Once the sauce is done cooking, add crab pieces and clams to the pot and simmer, covered until clams have opened, about 5 minutes. Discard any unopened clams.
Using a slotted spoon, transfer clams to a bowl and set aside.
Add shrimp, scallops and fish to the pot and simmer, covered until the fish is cooked through, about 5 minutes.
Return clams to pot and heat through.
Ladle the Cioppino into large soup bowls and garnish with chopped parsley or basil.
Serve with country style bread.