Literally a light broth, but usually a fish soup made with different kinds of fish and shellfish, with oil, garlic, tomatoes, onions, parsley and vinegar, and in the south maybe a hot pepper. Each region and town on the northern Adriatic has its own version; Grado is famous for it. You may also hear it called brodetto alla marinara.
The Marche, too, is especially proud of its version, with some 13 kinds of fish; it even has an Accademia to maintain its lofty standards. In the Abruzzo, the most famous fish soup comes from Vasto: brodetto vastese.