פּירוש אויף בראשית 1:20

“Let the waters bring forth swarms” [1:20]. The Holy One said on the fifth day that living things should swarm and become created from the water, flying things and all the fish, also the great fish, Leviathan and his wife. The Holy One saw that if Leviathan would have relations with his wife and have children, they might destroy the world with their strength. That is why the Holy One killed the female and pickled her in brine for the righteous to eat in the days of the Messiah. The Holy One killed the female and not the male, because if the female remained alive, she would have relations with other fish and would have large children who would have overturned the world.⁴¹B. Baba Bathra, 74b. However, if the male would have relations with other fish, their offspring would not be large fish.

The Holy One blessed the fish more than other creatures in that though people catch fish, yet they are free and have no master. This is because the Holy One wrote them a blessing that they should multiply even if many of them are caught.⁴²Rashi, Genesis, 1:22. The wild animals also don’t have any masters, are free and many of them are caught, yet the Holy One did not write a blessing for the wild animals because the snake was also a wild animal and the Holy One wanted to curse it. That is why the Holy One did not write a blessing for any wild animal so that the snake should not be included in the same blessing.⁴³Midrash Tadshe 1, in A. Jellinek, Bet ha-Midrash, 3: 164.

Several fish in this verse [1:21] are called “great sea monsters.” They are fish that are many hundreds of miles long, as the Talmud also discusses in [tractate] Baba Bathra, chapter five. Rabbah Bar Bar Hana said: “the sea cast up a fish so large that sixty cities ate from it and sixty cities pickled it in brine to eat from it. From one eye, three hundred measures of oil and fat were extracted. After a year I returned and people were sawing large pillars from the bones for buildings in the same city.”⁴⁴B. Baba Bathra, 73b.

נפש חיה LIVING CREATURES — Creatures that shall have vitality.