I have tried to read up and understand why shell fish aren't kosher, but the reasoning for scales/fins seems to be able to apply to shellfish as well. Is there any logical explanation?

  • 1
    Hi Luple, welcome to Mi Yodeya! I suppose you just gave the answer yourself. There are criteria for animals to be kosher, but there is no reasoning of the Torah behind them. Try to Google the word chok. Commented Jan 3, 2019 at 22:42
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    In what way does the reasoning seem to apply?
    – Alex
    Commented Jan 4, 2019 at 0:31
  • I think this is a reasonable question. @Luple is not asking which sea creatures are not kosher, but rather why. The answer may be, we don't know. There have certainly been attempts to explain it based on health issues (of the waters they come from) but that doesn't really fit. Are there historical answers? Other cultures that also eschew shellfish? Any specific physical or spiritual reasons for it, other than "G-d said so"?
    – Cyn
    Commented Jan 4, 2019 at 0:33
  • 2
    @cyn maybe that's what he's asking. There's no way to know unless he clarifies.
    – Double AA
    Commented Jan 4, 2019 at 1:07
  • related: judaism.stackexchange.com/questions/95340/…
    – Loewian
    Commented Jan 4, 2019 at 1:54

1 Answer 1


Shellfish do not have fins and scales. As the pasuk Shmini 11:9 says

Among all [creatures] that are in the water, you may eat these: Any [of the creatures] in the water that has fins and scales, those you may eat, whether [it lives] in the waters, in the seas or in the rivers.

**Rashi explains:

fins: Heb. סְנַפִּיר. These are [the wing-like appendages] with which it swims [namely, fins].

scales: Heb. קַשְׂקֶשֶׂת. These are the scales that are affixed to it, as it is said: “And he was wearing a coat of mail (קַשְׂקַשִּׂים) ” (I Sam. 17:5), [lit. armor of scales]. — [Chul. 66b]

The next pasuk is explicit.

But any [creatures]that do not have fins and scales, whether in the seas or in the rivers, among all the creeping creatures in the water and among all living creatures that [live] in the water, are an abomination for you.

This means that any sea creature of any type that does not have fins and scales is forbidden. This includes not only shell fish, but all other creatures living in the water (whether salt or fresh water). That is why sharks, dolphins and other sea creatures are forbidden.

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