Mahi Mahi is a fish called dolphin, not the mammal.
Yes, mahi-mahi is a fish, also known as dolphin. My point was that restaurants apparently feared putting `dolphin' (fish) on the menu; patrons might think it to be a mammal. So `mahi-mahi' it became. No confusion there.
BTW, shark is served in many forms, but not under that name.
Marketing.