Torah Portion: Shemini
“את זה תאכלו מכל אשר במים” (ויקרא יא ט)
It is a positive commandment to inspect the signs of a kosher fish — that is, when one wishes to eat fish, he must first examine it well to see whether it has the signs that the Torah provides to determine that it is of a kosher species, which are fins and scales — as it is written: This may you eat from everything that is in the water: everything that has fins and scales (Vayikra 11:9).
The root idea of this mitzvah has been elaborated above, with regard to the signs of kosher animals. The same rational applies here.
The laws of the mitzvah include: Any fish on which even a single scale was found does not have to be inspected [further] to see whether it has fins, for it is certain that it does. But a fish that has fins must be inspected further to see whether it has scales because there are many species of non-kosher fish that have fins [but not scales].
Any species of fish that by its nature has scales, even though while young it does not have them yet, is kosher. This is because the Torah is only particular about the species — whether fish of that species have scales — because it suits the nature of humans, and so even if this specific, individual fish did not yet grow its scales it is nevertheless kosher.
This mitzvah applies in all places and at all times, to both men and women.
