 Stockfish is very nutrient-rich and was consumed domestically, although it was during the boom in the stockfish trade in the late Middle Ages, that the product became accessible throughout Scandinavia, as well as the rest of Europe.The higher quality stockfish would be soaked in water, then boiled and eaten with melted butter.Lower grade qualities would be harder and more fuel consuming to boil and it has been suggested that adding ash from beech or birch in the boiling water, would break down the protein chains and speed up the process.