What is the difference between "Sheretz ha'Mayim" and "Nefeh ha'Chayah Asher ba'Mayim"?
Ramban (citing Ibn Ezra): The former refers to small vermin that are created by the water; the latter, water creatures that are created by a male and female.
Why does the Torah add the (otherwise superfluous) phrase "Sheketz heim lachem"?
Bearing in mind the Gemara in Kidushin 61a, that one can extrapolate positive from negative and negative from positive, having said above "es Zeh Tochlu ... ", why does the Torah need to insert this Pasuk Why can we not simply extrapolate from there what is forbidden?
A La'av that is derived from an Asei is like an Asei. The Torah therefore wrote "Kol Asher Ein Lo? Lo Sochlu" for a La'av (PF). Moshav Zekenim left his question unanswered, even though he cites the principle that a La'av derived from an Asei is like an Asei! It seems that words are missing. Perhaps he asks why the Torah repeated "Kol Asher Ein Lo?" in Pasuk 12. Rashi however answered this (refer to 11: 12:1:1! - PF)
What is "Nefesh ha'Chayah" coming to include?
Sifra: "Chayah" includes Chayos of the sea, and "Nefesh, sirens (a woman from the waist and up, and a fish from the waist down; who sings with a pleasant voice - Moshav Zekeinim) 1 .
Sifra: They are not Metamei be'Ohel however, since the Torah writes in Chukas, Bamidbar, 19:14 "Zos ha'Torah" to preclude them.