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.