The complaint was also filed against the novelist Daniel Kraus, an associate producer who has been credited with creating the “original idea” for The Shape of Water alongside Del Toro.
The works do have substantially different endings, and The Shape of Water has an important male character who does not resemble anyone in the play.
The copyright complaint filed in California this week marks the first legal action the Zindel family has taken against The Shape of Water, which is nominated for 13 Oscars, including best picture, best director, best original screenplay and three acting awards.
The Shape of Water, co-written by Del Toro and Vanessa Taylor, tells the story of a 1960s Baltimore laboratory cleaner who falls in love with a sea creature whom she tries to rescue.