Stockfish is divided into two main groups, round fish and split fish. Round fish has been gutted – i.e. the stomach has been slit and the innards and head removed. The fish are coupled together two by two with string tied around the tails, and are hung up like that to dry. Split fish is fish that has been decapitated and split along the belly and backbone, leaving it connected only at the tail. In Lofoten today, round fish is totally predominant.

The grading of stockfish is an old art dating back to the times when the Hanseats and the Dutch had control of stockfish trade in Bergen. Written sources from 1750 show that split stockfish was also sorted into many different classes.

Rotskjær Herrenfisk, Lübsk Zartfisk, Stor Zartfisk, Hollender Zartfisk,
Dansk Zartfisk, Kehlvækker fisk, Lübsk Vækkerfisk, Hamburger Høkerfisk, Dansk Høkerfisk, Lübsk Losfisk, Hamburger Losfisk
Middelfisk, Småfisk, Søndmør Rotskjær, Mager Rotskjær, Udskud Rotskjær,

In 1890, the multifarious sorting system was made simpler, and today?s split stockfish categories were adopted: Zartfisk, Vekkerfisk, Høkerfisk and Danskfisk.

(From: Bottolfsen, Ø. "Lüb og undermåls italiener" Lofotboka 1984)