If fish are a clade, people uninfluenced by internet memery would refer to all vertebrates as fish, yet I’m pretty sure this also doesn’t happen. If the guy in the restaurant today had told me that the varying fish on the menu was not sea bream, but a sodding gecko, I’d have been pretty miffed.
I’m confused why you think the common usage of the word fish has any relevance to a discussion about choosing a definition for a fish clade. I’m not making the claim that this is how people use fish in common usage. My claim is that if you want to draw a fish clade, the only consistent way to do that is to include all of vertebrata. Scientists defining clades don’t concern themselves with how laymen group animals together, because that would be dumb.
I’m confused why you think the common usage of the word fish has any relevance to a discussion about choosing a definition for a fish clade. I’m not making the claim that this is how people use fish in common usage. My claim is that if you want to draw a fish clade, the only consistent way to do that is to include all of vertebrata. Scientists defining clades don’t concern themselves with how laymen group animals together, because that would be dumb.