Why does the Torah insert the (otherwise superfluous) phrase "ve'Sheketz Yih'yu" Lachem?
Rashi: To forbid a mixture containing fish withut fins and scales if they add taste. 1
Seforno (on Pasuk 2): The Torah refers to the species that contaminate the soul but not the body 2 as Sheketz.
Targum Yonasan: To include the juice and the brine of Tamei fish in the Isur. 3
Pesachim, 23a: "Lachem" comes to permit the Tamei fish be'Hana'ah - overriding the principle that wherever the Torah writes a Lashon Achilah, it incorporates an Isur Hana'ah; whereas "Yih'yu teaches us that Lechatchilah one is forbidden to do business with forbidden species. 4
Why does the Torah write specifically "mi'Besaram Lo Socheilu"?
What is the word "Teshakeitzu" coming to teach us?
Rashi: It teaches us that ?Yavchushin? (gnats 1 ) that have been sifted are included in the prohibition.
Ramban:'Yavchushin' are not, but a kind of insect that grows in wine.
Targum Yonasan: It comes to place an Isur Hana'ah on Sheratzim. 2
Chulin, 67b: It comes to include the worms that are found between the skin and the flesh of an animal. 3
Why are fish not subject to Tum'ah?
Oznayim la'Torah #1: Because they live and die in the sea and in rivers, which are source of Taharah, the Torah did not decree Tum'ah on the enire species.
Oznayim la'Torah #2: The Torah decreed Tim'ah on all land creatures because they possess Neshamos, which is why the Chitzonim (demons) desire to cleave to them when they die in order to feed from the Kedushah of the Neshamah that remains ? the higher the level of Neshamah, the stronger the Tum'ah. 1 The sole exception is that of the fish, which do not possess a Neshamah, and which are therefore not subject to Tum'ah, since the Chitzonim do not desire them.
See Oznayim la'Torah, who elaborates in detail.
QUESTIONS ON RASHI
Rashi writes that "ve'Sheketz Yih'yu" forbids a mixture containing them if they add taste. Bur we have other sources to forbid a mixture with taste of Isur?
Moshav Zekenim: One might have thought that brine is a mere secretion. Even though another Pasuk forbids it, if not for this Pasuk, we might have thought that their mixture is permitted.
Rashi writes that "ve'Sheketz Yihyu" forbid a mixture containing them if they add taste. But the Sifra gives different Shi'urim of Bitul, and one of them is one part in a hundred and ninety-two?
Mizrachi: Perhaps the Sifra is discussing Miyn be'Miyno, whereas Rashi is referring to Miyn be'she'Eino Miyno.
Gur Aryeh: The Tana'im in the Sifra argue about how much gives taste. R. Yehudah holds that it is very potent, therefore the Shi'ur is one part in a hundred and ninety-two.
