More expensive versions may add langoustine (Dublin Bay prawn; Norway lobster), though this was not part of the traditional dish made by Marseille fishermen.

The broth is traditionally served with rouille, a mayonnaise made of olive oil, garlic, saffron, and cayenne pepper, on grilled slices of bread.

[3] According to the Michelin Guide Vert, the four essential elements of a true bouillabaisse are the presence of rascasse, the freshness of the fish; olive oil, and excellent saffron.

[4] The American chef and food writer Julia Child, who lived in Marseille for a year, wrote: "to me the telling flavor of bouillabaisse comes from two things: the Provençal soup base—garlic, onions, tomatoes, olive oil, fennel, saffron, thyme, bay, and usually a bit of dried orange peel—and, of course, the fish—lean (non-oily), firm-fleshed, soft-fleshed, gelatinous, and shellfish.

These are the typical ingredients used in one of the most traditional Marseille restaurants, the Grand Bar des Goudes on Rue Désirée-Pelleprat:[6] Four kilograms of fish and shellfish, including, on a typical day, grondin (sea robin), Rascasse (Scorpaena scrofa), rouget grondin (red gurnard), congre (conger eel), baudroie (lotte, or monkfish), Saint-Pierre (John Dory), vive (weever), and sea urchins.

The rouille, a spicy mayonnaise which is spread on thick slices of country bread and floated on the bouillabaisse when served, is made with an egg yolk, two cloves of garlic, a cup of olive oil, and ten pistils of saffron, and is seasoned with salt and Cayenne pepper.

Next olive oil is put into a large casserole, and onions, cleaned and sliced, are added, along with crushed garlic and tomatoes, peeled and quartered, without seeds.

[7] Another version of the classic Marseille bouillabaisse, presented in the Petit Larousse de la Cuisine, uses congre, dorade, grondin, lotte, merlan, rascasse, saint-pierre, and velvet crabs (étrilles), and includes leeks.

In this version, the heads and trimmings of the fish are put together with onions, celery and garlic browned in olive oil, and covered with boiling water for twenty minutes.

Then the vegetables and bouquet garni are added, and then the pieces of fish in a specific order; first the rascasse, then the grondin, the lotte, congre, dorade, etrilles, and saffran.

[9] The French screenwriter and playwright Marcel Pagnol, a member of the Académie française and a native of Marseille, showed his own idea of a proper bouillabaisse in two of his films.