Fish stock is liquid made from seasoning, water, and fresh fish parts. Similar to broth, it often serves as part of the liquid base in seafood soups, stews, and chowders. Stock is frequently preferred to water for soups and stews because it adds an extra seafood flavor. Unlike chicken or beef stock, which is made using a similar process, fish stock does not need to be cooked for hours. Although fish stock can be found commercially, it is more often homemade.
White fish, such as flounder, cod, or red snapper, is normally used to make fish stock. Since white fish is leaner than oily fish, it is more desirable for the stock. Only the bones, heads, and, sometimes, fins are used. The gills are removed from the head before it is included in the stock.
In addition to the fish parts, onions, carrots, and celery are normally added. Black peppercorns and salt are popular additions for seasonings. Dry white wine or white wine vinegar combined with water usually serves as the liquid element. Either olive oil or butter is included for sauteing as well.
Many versions of fish stock add a bundle of spices, termed a herb bouquet or sachet d'épices. The spice bag usually consists of fresh or whole herbs, such as bay leaves, thyme springs, and garlic cloves, wrapped and tied in cheesecloth. Parsley stems and whole cloves are also sometimes included. Wrapping the herbs in cheesecloth allows the flavors to combine with the stock without stray herbs floating in the liquid.
To make fish stock, the vegetables are usually sauteed in olive oil, and sometimes the fish bones are sauteed with them. Afterward, the rest of the ingredients are added. When all the elements have been included, the stock is first brought to a boil and then simmered for about half an hour. During simmering, any foam that forms on the surface of the liquid can be skimmed off.
Once complete, the stock is sieved, usually through layers of cheesecloth. Any solids are disposed of and only liquid should be kept. The fish stock can immediately be used for a soup, stew, sauce, or chowder, or it can be covered and refrigerated for up to two days. It also may be frozen for about two months. When chilled, any excess fat that forms on the surface should be skimmed off before the stock is used in a recipe.