All About Kosher Fish

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The Biblical Source

People who keep the kosher laws follow the directions written in the Tanach, or the Five Books or Moses. Leviticus 11:9 lists two signs of a kosher fish, “snapir v’kaskeses,” or fins and scales. This is the reason why shellfish are not considered kosher, as they have neither fins nor scales. The Talmud testifies that all fish that have scales also have fins (although the opposite is not true), so to identify a kosher fish, it is only necessary to ensure that it has scales.

What Are Kaskeses?

To be more precise, however, kaskeses do not refer to any type of scale. Instead, kaskeses refer to scales that can be removed easily, either manually or with a knife, without damaging the fish’s skin. Therefore, most opinions hold that sturgeon is not kosher because its ganoid scales cannot be easily detached from its skin. The same would be true of swordfish, which some believe has scales that are embedded in its skin to the degree that it would be impossible to remove them without puncturing the skin.

Preparation of Kosher Fish

Although a fish may be known to be a kosher species of fish, it must be prepared correctly in order to make sure that no non-kosher fish could get mixed with the kosher species. For example, a person who keeps kosher cannot rely on a sign in a fish market to identify a fish, or even the testimony of the layman behind the counter. To know that a fish is kosher, it must either still have the scales attached or be identified by a person who both keeps strict kosher laws and is experienced in identifying specific species of fish. It also must be cut with a different knife and on a different cutting board from non-kosher fish, and the person cutting it should wash her hands or change her gloves before touching the kosher fish.

List of Common Kosher Fish

The following list is not exhaustive, but it does contain several fish that are commonly eaten by those who keep kosher:

  • Tuna
  • Salmon
  • Tilapia
  • Whitefish
  • Chilean sea bass
  • Flounder
  • Herring
  • Mackerel