Heat the oil in large heavy soup pot over low heat. Add the onion,bell peppers, and garlic and cook, covered until the vegetables are tender, about 25 minutes.
Add the fish stock,Zinfandel, and tomatoes and raise the heat.
Stir in the basil,thyme, and bay leaf, and season with salt,pepper and red pepper flakes.
Bring the soup to a boil,reduce the heat and simmer, partially covered for 30 minutes. Stir occasionally,crushing tomatoes with the stirring spoon. Taste and correct the seasoning. (If you wish to complete the soup through this step the day before serving, it will keep and improve upon refrigeration.)
Scrub the mussels and clams well and debeard the mussels. Place them in a heavy pot, add water to a depth of 1 inch,cover and set over high heat. As they steam open, remove the mussels and clams one by one with a slotted spoon and reserve. Discard any shellfish that haven't opened after 5 minutes. Freeze the shellfish juices for your next batch of fish stock.
Rinse shrimp and scallops and pat dry.
At 5 minutes before serving the stew, bring the tomato and wine mixture to a boil. Drop in the shrimp and scallops, then the clams,mussels in their shells. Add the parsley, stir well, and remove from the heat. Let stand,covered, for 1 minute.
Ladle the stew into heated bowls, dividing the seafood equally and serve immediately.