Anchovies are small -- up to about 6 inches, or 20 cm -- bluefish that swim in schools, and are caught in enormous numbers in the Mediterranean. Much of the catch is preserved, either under salt or in oil, and though an anchovy filet packed in oil is quite nice drained and draped over a piece of buttered bread, they are most often used as an ingredient, imparting a salty hint of the sea more than fishy flavor per se.

They are also nice fresh, and quite easy to prepare. This antipasto is from Livorno, on the Tuscan coast:

Acciughe Alla Povera - Poor Man's Anchovies

To serve 4:
2 1/4 pounds (1 k) fresh anchovies
4 medium onions, sliced into very fine rings
The juice of a lemon
1/2 cup white wine vinegar
Extravirgin olive oil
Salt and pepper

Split the anchovies up the middle, gut them, and remove their heads and spines. Rinse them drain them, and lay them out in a container, with three of the onions.

Combine the vinegar and lemon juice and drizzle the mixture over the fish. Marinate the fish in a cool place for 3-4 hours. When the flesh of the anchovies has whitened and firmed up (the acidity will cook it) drain them and transfer them to a different bowl. Season them lightly with salt and pepper, add extravirgin olive oil to cover, and garnish them with the rings made from the remaining onion. Let the fish rest for a few more hours in the fridge, and serve them as an antipasto.

Anchovies are also called Alici in Italy, and I have seen fishmongers with both on display -- I assume the distinction is based on size, because it's the same fish.

Anchovy Recipes on About:
Anchovy Twists, a tasty antipasto.
Grilled Anchovies, a recipe that will work with any small fish.

How to Select Fresh Fish
Other Fish Recipes