My point is that scientists do not define a fish clade precisely because to do so would be so far removed from the common understanding of the word fish, and there being a different term for the same thing to hand.

And this is the point I’m making because I believe further up the thread people were saying stuff based on a false impression that you had to think of “fish” cladistically in some situation or other, and hence that some creatures were fish when in fact they are not.