What a silly movie. Mr. Peabody (William Powell) hears, goes searching for, and then fishes from the sea (dare I say kidnaps?) a young mermaid. The mermaid is of course completely content to swim around in Mr. Peabody's fancy goldfish pond, just as long as he will kiss her every once in a while. Did I mention there is a somewhat suspecting but also confused by the particulars Mrs. Peabody?
There is water-spitting, lying, swimming, a psychiatrist... 
One star for the moment in the film when a woman who desperately wants to win Mr. Peabody's attention goes swimming in the fish pond and has an underwater fight with the mermaid. But that's all. Go rent I Married a Witch.