John Gill Commentary Genesis 7:22

"all in whose nostrils was the breath of the spirit of life, of all that was on the dry land, died." — Genesis 7:22 (ASV)

All in whose nostrils [was] the breath of life
Whether of fowls, beast, cattle, or creeping things:

of all that was in the dry land, died ;
by which description fishes were excepted, since they do not breathe, having no lungs, and are not on the dry land, where they cannot live, but in the waters. Some pretend it to be the opinion of some Jewish writers, that the fishes did die, the waters being made hot, and scalded them; but this fable I have not met with.