Fishes in the Ark?

Question

How can we know there weren't fishes in the Ark?

When we learn Noah, we take for granted that the sea animals weren't in the Tevah. But when we read literally the Torah, it says "7 pairs of clean (Kosher) animals and a pair of unclean animals"; it doesn't mention anywhere that's every animal excluding the sea animals, though it may seem obvious.

מִכֹּל | הַבְּהֵמָה הַטְּהוֹרָה תִּקַּח לְךָ שִׁבְעָה שִׁבְעָה אִישׁ וְאִשְׁתּוֹ וּמִן הַבְּהֵמָה אֲשֶׁר לֹא טְהֹרָה הִוא שְׁנַיִם אִישׁ וְאִשְׁתּוֹ׃

Of all the clean animals you shall take for yourself seven pairs, a male and its mate, and of the animals that are not clean, two, a male and its mate.

Answer 1

Fish were not harmed:

the Gemara notes that marine life was not harmed by the Mabul. (Sanhedrin 108a, quoted by Rashi on Bereshis 7:22)

that were on the dry land: But not the fish, which were in the sea. — [Sanh. 108a]

Maharsha says that only the water that covered the land was boiling hot. Others say that a cone of water under the ark was prepared to allow the fish to survive.

Note that since the entire Earth was covered with water, the fish also survived by a miracle since otherwise fresh water and sea fish would not have survived because of the mixing of the various types of water.

Answer 2

Midrash Bereishis Rabbah 32:11 cites a yesh omrim arguing that fishes were in fact included among those who were to be in the teiva but they fled to the ocean.

מכל אשר בחרבה מתו : פרט לדגים וי"א אף הן היו בכלל מאוספין, אלא שברחו לים הגדול לאוקיינוס.