In The Diaries of Adam and Eve, Adam mistakes his son Cain for a fish. He says:

"It resembles us in some ways, and may be a relation. That is what she (Eve) thinks, but this is an error, in my judgment. The difference in size warrants the conclusion that it is a different and new kind of animal--a fish, perhaps, though when I put it in the water to see, it sank, and she plunged in and snatched it out before there was opportunity for the experiment to determine the matter."