Season the fillets generously with salt and cayenne. Combine the onions, bell peppers, celery and garlic in a bowl and season with salt and cayenne.
Heat the butter in a deep, heavy pot over medium heat. Put two to three fillets of fish in the bottom of the pot in the butter. Then add one-third of the vegetable mixture, then one-third of the tomatoes. Continue making the layers until all the ingredients are used. Put the shrimp, crabmeat and bay leaves over the final layer. Pour in the wine, cover and reduce the heat to medium-low. Simmer for one hour (do not remove the lid).
To serve, put a slice of French bread in the bottom of a soup bowl, then ladle the soup over it and pass the rouille.