Answer (Ravina): Chachamim of Eretz Yisrael teach that we may insert a Prat between two Kelalim that are written together to make a Klal u'Frat u'Chlal;

"In water" is a Klal. "In seas and rivers" is a Prat. The second "in water" is another Klal. The Klal Prat u'Chlal teaches what is similar to the Prat, i.e. all flowing water;

This includes Charitzin u'Ne'itzin, to forbid (fish in them without Simanim);

We exclude pits and caves, to permit (fish in them without Simanim).

Question: Perhaps just like the Peratim are bodies of water in the ground (but not in Kelim), we include all such cases, i.e. (Charitzin u'Ne'itzin, and even) pits and caves. In them, fish without Simanim are forbidden!

We would exclude Kelim. (In them, fish without Simanim are permitted.)

Answer: If so, the repetition "you may eat" would not teach anything.

Answer #2 (to Question 3:f, 66b - Tana d'Vei R. Yishmael): We do not expound "in water... in water" according to Klal u'Frat, rather, like Ribuy and Mi'ut (inclusions and exclusions);

"In water" is a Ribuy. "In seas and rivers" is a Mi'ut. "In water" is another Ribuy;

The first Ribuy (initially) includes everything, i.e. Charitzin u'Ne'itzin to forbid;

A Ribuy Mi'ut Ribuy includes everything (except for what is totally unlike the Mi'ut);

We include Charitzin u'Ne'itzin, to forbid;

We exclude pits and caves, to permit.

Question: Perhaps we include pits (to forbid), and exclude Kelim (to permit)!

Answer: If so, the repetition "you may eat" would not teach anything.

Question: We could say oppositely! (We include Charitzin u'Ne'itzin to permit, and exclude pits and caves to forbid.)

Answer (Matisyahu ben Yehudah's Beraisa) Question: Why do we include pits and caves to permit, and exclude Charitzin u'Ne'itzin to forbid?

Answer: We include pits to permit, for they are still water, like in Kelim. We exclude Charitzin u'Ne'itzin and forbid, for they are not still, unlike Kelim.

Question: (We said (3:e, 66b) that the Torah permitted fish without Simanim explicitly and Stam.) Which source is called explicit, and which is Stam?

Answer #1 (Rav Acha or Ravina): "You may eat (... what has the Simanim)" is the explicit source. "(What lacks the Simanim... ) you may not eat" is Stam.

The former is explicit, for it says "those you may eat" right after "in seas and rivers";

The latter is Stam, for "you may not eat" is not written adjacent to "in seas and rivers."

Answer #2 (the other of Rav Acha and Ravina): "You may eat" is Stam. "You may not eat" is explicit.

The former is Stam, for we could have understood it to mean that in Kelim, all fish (even with Simanim) are forbidden;

The latter is explicit, for it surely permits all fish in Kelim (and shows that also the former verse permits them).

(Rav Huna): One should not strain (date) beer through a wooden strainer at night, lest a worm alight on the strainer and fall into the cup;

Since the worm (once) separated from the beer, it is considered "a Sheretz that swarms on the ground" (and is forbidden).

Question: If so, one should not drink beer in a Kli, lest a worm alighted on the Kli and returned to the beer!

Answer: In that case, it is considered as if the worm never left the water. (It is permitted.)

Support (Beraisa): "You may eat anything in water" permits bending down to drink from pits (even though one may ingest worms).

Question: We should be concerned lest the worms alighted on the wall of the pit!

Answer: Since they never left the pit, they are permitted.

Similarly, if a worm in beer separated to the Kli wall, it is still permitted.

Rav Chisda: A Beraisa supports Rav Huna.

(Beraisa): "Every Sheretz that swarms on the ground" includes flies that were strained from wine.

Inference: Had they not been strained, they would be permitted.

(Shmuel): If a gourd grew wormy while attached, the worms are forbidden due to "every Sheretz that swarms on the ground". (Since it is attached, it is as if the worm is on the ground.)

Suggestion: An apparent contradiction of Beraisos supports Shmuel:

(Beraisa #1): "On the ground" excludes mites in lentils, chickpeas, dates and figs.

Contradiction (Beraisa #2): "Every Sheretz that swarms on the ground" includes worms in the roots of olives or vines.

Answer: Both Beraisos discuss mites in produce. In the former, they grew while the produce was attached. In the latter, they grew after it was detached.

Rejection: No, in both Beraisos they grew when the produce was attached;

Beraisa #1 discusses mites (that started) in the produce. Beraisa #2 discusses mites of the tree itself.

Support: Beraisa #2 says 'worms in the roots of olive trees or vines'.

Questions (Rav Yosef): If a worm separated and died immediately, or, if it entered the air (but never landed on the ground), what is the law?

Questions (Rav Ashi): What is the law if a worm separated to the outside of the date, or to the outside of the date pit, or from one date to another?

These questions are unresolved.

Version #1 (Rav Sheshes brei d'Rav Idi): Worms (most Rishonim - in fish innards; Rashi - in the lungs or liver of an animal) are forbidden.

This is because they came from outside, i.e. they were ingested.

Objection (Rav Ashi): If they were ingested, they would be found (also) in the end of the digestive tract!

Version #2 (Rav Sheshes brei d'Rav Idi): The worms are permitted.

This is because they grow from it (the fish or animal) itself.

(Rav Ashi): This is obvious. If they were ingested, they would be found in the end of the digestive tract! (end of Version #2)

The Halachah is, they are forbidden, because they enter through the respiratory system during sleep.

Worms underneath the skin in animals are forbidden. In fish, they are permitted.

Ravina asked his mother to mix fish worms with his fish, so he would eat them without seeing them.

Question (Rav Mesharshiya brei d'Rav Acha): What is the difference between worms in animals and worms in fish?

Answer (Ravina): Animals (and worms inside) are forbidden until slaughtered. Shechitah does not permit the worm;

Fish are permitted without Shechitah, so also worms that grow inside are permitted.

(Beraisa): "That goes on its belly" refers to a snake. "All" includes long worms. "Four legs" refers to a scorpion. "All that goes" includes beetles. "Many legs" refers to a centipede. "Until every" includes similar species, and species similar to those.

(Beraisa - R. Yosi Dormaskus): Livyason (a giant sea creature that Tzadikim will eat in the end of days) is a Tahor fish.

"Its protection" is its scales. "Under it are rays of sun" are its fins.