A Fischbrötchen or Fischsemmel (lit. fish sandwich) is a sandwich

Sandwich

A sandwich is a food item, typically consisting of two or more slices of :bread with one or more fillings between them, or one slice of bread with a topping or toppings, commonly called an open sandwich. Sandwiches are a widely popular type of lunch food, typically taken to work or school, or...

 made with fish

Fish

Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...

 and onion

Onion

The onion , also known as the bulb onion, common onion and garden onion, is the most widely cultivated species of the genus Allium. The genus Allium also contains a number of other species variously referred to as onions and cultivated for food, such as the Japanese bunching onion The onion...

s, sometimes also made with remoulade

Remoulade

Remoulade or rémoulade, invented in France, is a popular condiment in many countries. Very much like the tartar sauce of some English-speaking cultures, remoulade is often aioli- or mayonnaise-based. Although similar to tartar sauce, it is often more yellowish , often flavored with curry, and...

 and pickles

Pickles

Pickles may refer to:* A pickled cucumber, the food most commonly referred to as a pickle in the U.S. and Canada* A pickled onion, the food most commonly referred to as a pickle in the UK* Other vegetables that have been pickled...

. It is commonly eaten in Northern Germany

Northern Germany

- Geography :The key terrain features of North Germany are the marshes along the coastline of the North Sea and Baltic Sea, and the geest and heaths inland. Also prominent are the low hills of the Baltic Uplands, the ground moraines, end moraines, sandur, glacial valleys, bogs, and Luch...

, due to the region's proximity to the North Sea

North Sea

In the southwest, beyond the Straits of Dover, the North Sea becomes the English Channel connecting to the Atlantic Ocean. In the east, it connects to the Baltic Sea via the Skagerrak and Kattegat, narrow straits that separate Denmark from Norway and Sweden respectively...

 and Baltic Sea

Baltic Sea

The Baltic Sea is a brackish mediterranean sea located in Northern Europe, from 53°N to 66°N latitude and from 20°E to 26°E longitude. It is bounded by the Scandinavian Peninsula, the mainland of Europe, and the Danish islands. It drains into the Kattegat by way of the Øresund, the Great Belt and...

.

The most common preparation is made with Bismarck Herring

Herring

Herring is an oily fish of the genus Clupea, found in the shallow, temperate waters of the North Pacific and the North Atlantic oceans, including the Baltic Sea. Three species of Clupea are recognized. The main taxa, the Atlantic herring and the Pacific herring may each be divided into subspecies...

 or soused herring

Soused herring

The term soused herring usually means 'soaked in a mild preserving liquid', and can be used to refer to raw herring in a mild vinegar pickle or the famous Dutch brined herring...

. Other varieties use Brathering

Brathering

Brathering is a simple German dish of fried, marinated herring.In a common recipe, whole, green herrings are either breaded or simply turned in flour, then fried, and finally pickled in a marinade of vinegar and briefly boiled water, onion, salt, spices like pepper, bay leaves and mustard seeds...

, rollmops

Rollmops

Rollmops are pickled herring fillets, rolled into a cylindrical shape around slices of onion, pickled gherkin, or green olive with pimento. Rollmops can be served held together with one or two small wooden skewers....

, European sprat

European sprat

The European sprat, Sprattus sprattus, also known as bristling, brisling or skipper, is a small, herring-like, marine fish. Found in European waters, it has silver grey scales and white-grey flesh. Specific seas in which the species occurs include the Irish Sea, Baltic Sea and Sea of the Hebrides...

, salmon

Salmon

Salmon is the common name for several species of fish in the family Salmonidae. Several other fish in the same family are called trout; the difference is often said to be that salmon migrate and trout are resident, but this distinction does not strictly hold true...

, smoked Atlantic mackerel

Atlantic mackerel

The Atlantic mackerel , is a pelagic schooling species of mackerel found on both sides of the North Atlantic Ocean. The species is also called Boston mackerel, or just mackerel....

, other fried fish varieties (e.g. fish burgers). Prawns

Crangon crangon

Crangon crangon is a commercially important species of shrimp fished mainly in the southern North Sea, although also found in the Irish Sea, Baltic Sea, Mediterranean Sea and Black Sea, as well as off much of Scandinavia and parts of Morocco's Atlantic coast...

 are sometimes used, as are various other species of food fish. Fischbrötchen are commonly served at fast food

Fast food

Fast food is the term given to food that can be prepared and served very quickly. While any meal with low preparation time can be considered to be fast food, typically the term refers to food sold in a restaurant or store with preheated or precooked ingredients, and served to the customer in a...

 stands or take-out

Take-out

Take-out or takeout , carry-out , take-away , parcel , or tapau , is food purchased at a...

 restaurants.

The Hanover Fair was initially known as the Fischbrötchen fair due to the food rationing still in place in 1947.