In a large stockpot over high heat, add olive oil and slowly cook onions and garlic until soft and translucent, about 10 minutes. Add the basil, parsley, oregano, thyme and black pepper. Season with salt. Add dry red pepper, if desired. Add canned tomatoes and tomato sauce and bring to a boil. Add stock and wine and reduce heat to a simmer.
About 15 to 20 minutes before serving, start to add seafood. Add the crabs as they will take about 15 to 18 minutes to cook. About 3 to 5 minutes after the crabs are added, add the clams and/or mussels. About 10 minutes later, add the prawns. After 2 minutes, add the scallops and fish fillets and cook for 3 minutes, or until the clams and/or mussels open. Discard any unopened shellfish.
Serve in bowls with bread.