Evolution wasted its time making fish move around, vision, reproduction, gills and so on.

The replacement just has to taste very similar, not hurt animals, be reasonably priced, sustainable to produce and healthy or neutral for health.

Also, the meat substitutes that currently exist are all based on plants, which also went through all those years of evolution – they’re not chemically synthesized from the ground up. And they seem set to be supplanted in the future by meat grown artificially from real animal cells, which will make the whole point moot.

Food science isn't a linear process based on the evolutionary complexity of the organisms we eat.

Arguably cows have been impacted by as much evolution as any organism. It's not as though cows spontaneously generated 100M years ago - there were hundreds of millions of years leading up to cows becoming what we recognize today.

I don't think those numbers have any relationship to taste, but if you insist - life first appeared on earth 3.5 billion years ago, so the majority of that will be the exact same, it should take a minor modification to get to fish.

It doesn't have to be better than fish in every way. Just in the ways that consumers care about.