acqua pazza

Literally 'crazy water', this was first used around Naples for poaching fish and shellfish in sea water, as a way of saving money on salt, with tomatoes and olives and olive oil added after the fish was cooked.

Today cooks use a court bouillon or broth of tomatoes and herbs, then add a huge variety of other ingredients. It's nearly always a soup but you may see acquapazza on the menu, referring to an entire poached fish.