My preference, for a more rustic presentation, is to make the tomato sauce and fish broth separately, then combine the two when you're ready to cook the fish. While every bouillabaisse recipe calls for both saffron and fennel, the ways in which fennel is used is much more varied. Normally inedible, the green stalks of fennel can be included when making the fish broth. Other seasonings include orange rind, thyme, bay leaves and basil. Most bouillabaisse versions call for rouille, a kind of mayonnaise spiced with saffron, garlic and chili peppers, that is either swirled into the finished stew at the table, or served on top of bread.
Some versions use dried chili peppers, others just powdered cayenne pepper.
Schwertner uses a special chili pepper from the Pyrenees. Here is my bouillabaisse recipe for six to eight people. Place 3 tablespoons of oil in a nonreactive, 8-10 quart pot over medium heat. Add onions, fennel and garlic and cook until onions and fennel are soft, but not brown. Season with salt and pepper.