Halakhah su Levitico 11:47

Turbot is a case in point. The fish, known in Latin as Rhombus maximus and in German as Steinbutt, possesses bony tubercles but lacks the type of scale which qualifies as kaskeset. Rabbi David Feldman, Shimushah shel Torah (London, 5711), p. 19, reports that turbot is easily mistaken for kosher species such as plaice and halibut. Rabbi Feldman presents a simple method for determining whether a given fish of this type is of a kosher variety or is the non-kosher turbot. Both the kosher and non-kosher species are black on one side and white on the other. However, the various species differ in that the left side of the turbot is black, while in kosher species it is the right side which is black. Accordingly, to determine whether the fish in question is kosher or non-kosher, the fish should be held spine upward with the head pointing away from the body of the holder. If the black side of the fish is observed to be on the left, it may be concluded that the fish is a turbot. If, however, the left side of the fish is white, the fish may be presumed to be of a kosher species. Rabbi Feldman hastens to add that since this criterion is not formulated in talmudic sources it should not be regarded as absolute.³According to some authorities, there may be a positive reason to examine further for the presence of scales. Sefer ha-Ḥinnukh, no. 145, regards Leviticus 11:9 as a positive commandment establishing a requirement to examine fish for the presence of fins and scales prior to eating. This requirement cannot be satisfied by examining for the presence of other criteria; cf., Ḥiddushei Ḥatam Sofer, Ḥullin 66a, s.v. u-ve-dagim. Sefer ha-Ḥinnukh seems to follow Rambam’s formulation of this miẓvah as presented in his Sefer ha-Miẓvot, miẓvot aseh, no. 152. However, a somewhat different exposition is presented by Rambam in his Mishneh Torah, Hilkhot Ma’akhalot Assurot 1:1. Cf., also Rashi, Leviticus 11:47, and the comments of R. Elijah Mizraḥi, ad locum. For a fuller discussion of these sources, see the opening section of this writer’s article in the Kislev 5749 issue of Or ha-Mizraḥ. Accordingly, a careful examination of the scales should always be made before the fish may be accepted as a member of a kosher species. However, if it is determined that the left side is black, it may be concluded that the fish is a non-kosher turbot and hence any further investigation is without purpose.

The command of checking the signs of a beast or animal: That we were commanded to check the signs of a [domesticated] beast or [wild] animal when we want to eat of them - and they are that it brings up (chews) its cud and completely splits [its hoof], as it is stated (Leviticus 11:2-3), "This is the animal that you shall eat, from every beast upon the earth: All that separate the hoof, etc." And the language of Sifri, Shemini, Chapter 3:1 is "'It shall you eat' - it is for eating, but an impure animal is not for eating"; meaning to say, and we learn from it a negative commandment for an impure animal. And a negative commandment like this is called a negative commandment that comes from the implication of a positive commandment. And it is stated in another place, "And you shall differentiate between a pure beast and an impure, etc." (Leviticus 20:25). And it is also written (Leviticus 11:47), "To differentiate between the impure, etc."