La sirena y el pescador is a traditional folktale of the Rio Balsas region of Mexico, written in the Nahuatl language of San Agustín Oapan, Guerrero and accompanied by a Spanish translation. It tells the story of a young boy who must escape from his family after “Aalamatsin”, the mermaid and mother of all fish, wants the boy as a sacrifice in exchange for the release and pardon of his father, who betrayed his own wife and exploited the inhabitants of the river by overfishing it.