“I took a live mermaid not far from here one morning,” said John Counts. And then he paused. “That pause, old Wiedervogel,” he said after a bit, “that pause was for you to say ‘Incredible!’ or something similarly apropos.”
“Consider it said. Was she real?”
“She said that she was. She seemed to be. She was ugly as sin, to use an old phrase. Her skin was green and rough, and perhaps it was scaled. She had a deformity of her feet and legs that turned them into serviceable flippers. She smelled like a mermaid, or at least like a fish. She was a diver, and it was as such that her husband made his living from her. Her hair would have been human hair, if the infestations that lived in it had been cleaned out.”
“What did you do with her?”
“I tried to sell her in England. There is a man there who goes in for such things. ‘But I already have a mermaid,’ this man said. ‘A real one?’ I asked him. ‘No, not a real one, but this is not the first real one that has been offered to me. What I have is better than a real one.’
“It was. What the man had was incomparably better than a real one. She was a beautiful human girl who happened to terminate in a fishtail. But she was no great whiz at swimming or deep diving. She wasn't a real mermaid. I gave my mermaid back to her husband on my return voyage and paid him for her service. We did not understand the same thing by the term, but she was a real mermaid.”
“I used to see them sometimes,” said Wiedervogel.
~R. A. Lafferty, 'Pheonic' (1960)