Riiiight, because a flood would kill fish.
You must have not read my explanation in #29 Noah’s flood was God unleashing the tremendous stores of water both in the atmosphere and underground, all over the world at once. The force was so great that it caused great trauma to the earth. Fish in shallow water, rivers, streams, lakes would have been tossed around, even out of the water in some places, in this upheaval. It was not a gentle rain and slow filling of water. The forces were mighty and disastrous.