Hello fish friends! Today is the vampire squid a real cutie! Named after its distinct color and appearance, it is the only living cephalopod that is a scavenger. It also has the largest eyes proportional to its body in the animal kingdom. It lives 2-3000feet deep so unfortunately seeing these beauties in person isnt easy. They also cant change colors like other cephalopods or shoot out ink, because both would be pointless in the darkness of that depth. Instead, when threatened, they shoot out a bioluminescent mucus. As cool as this is, I dont want to be sneezed on by a squid.
My position is literally that of modern evolutionary biology. Fish is not really an accepted scientific term anymore because it doesn’t really mean much. Coelacanths are more closely related to humans than they are to trout, which are more closely related to you and me than they are to sharks. Dolphins, obviously being mammals are much more closely related to us like you said than any of those, but you still can’t not classify them as fish. Clint’s Reptiles is a great youtube channel made by an evolutionary biologist that does some good crash courses on the modern science if you want to understand it better.