"A Perfect Day for Bananafish" is a short story by J. D. Salinger, originally published in the January 31, 1948, issue of The New Yorker. It was anthologized in 1949's 55 Short Stories from The New Yorker, as well as in Salinger's 1953 collection Nine Stories. The story is an enigmatic examination of a young married couple, Muriel and Seymour Glass, on vacation in Florida. It is the first of his stories to feature a member of the fictional Glass family.

When the 28-year-old Salinger submitted the manuscript to The New Yorker in January 1947, titled "The Bananafish", its arresting dialogue and precise style were read with interest by fiction editor William Maxwell and his staff, though the point of the story, in this original version, was considered incomprehensible.

At Maxwell's urging, Salinger embarked upon a major reworking of the piece, adding the opening section with Muriel's character, and crafting the material to provide insights into Seymour's tragic demise. In frequent consultation with editor Gus Lobrano, Salinger revised the story numerous times throughout 1947, renaming it "A Fine Day for Bananafish". The New Yorker published the final version as "A Perfect Day for Bananafish" one year after Salinger first submitted the manuscript.

The story met with immediate acclaim, and according to Salinger biographer Paul Alexander, was "the story that would permanently change his standing in the literary community." Salinger's decision to collaborate with Maxwell and The New Yorker staff in developing the story marked a major advance in his career and led to his entry into the echelon of elite writers at the journal. The story has been compared to F. Scott Fitzgerald's "May Day."

The story is set at a large seaside resort in Florida. Muriel Glass, a wealthy and self-absorbed woman, phones her mother from her suite to discuss her husband Seymour, a World War II combat veteran recently discharged from an army hospital; it is implied that he was being evaluated for a psychiatric disorder. Muriel's mother is concerned by reports of her son-in-law's increasingly bizarre and anti-social actions, and warns her daughter that the doctor said he may "lose control of himself". Muriel dismisses her remarks as hyperbole, regarding her husband's idiosyncrasies as benign and manageable.

Meanwhile, at the resort's adjoining beach, a child named Sybil Carpenter has been left unsupervised by her mother so that she may drink at the hotel bar. Sybil wanders on the beach and finds Seymour, lying in solitude a quarter-mile from the hotel. Sybil reproaches Seymour for allowing another little girl, Sharon Lipschutz, to sit with him the previous night as he played the lounge piano for the hotel's guests. Seymour attempts to placate Sybil by suggesting they "catch a Bananafish", but Sybil insists that Seymour choose between her and Sharon Lipschutz. Seymour responds that he observed Sybil abusing a hotel patron's dog, and the girl falls silent.

Seymour places Sybil on a rubber raft and wades into the water, where he tells her the story of "the very tragic life" of the bananafish: they gorge themselves on bananas, become too large to escape their feeding holes, and die. Sybil is unfazed by the story, and claims that she sees a bananafish with six bananas in its mouth. Seymour affectionately kisses the arch of one of her feet, and returns her to shore, where she departs.

Once alone, and returning to the hotel, Seymour becomes less affable. He starts a baseless argument with a woman in an elevator, accusing her of staring at his feet and calling her a "god-damned sneak". He returns to his hotel room, where his wife is taking a nap. He retrieves a pistol from his luggage and shoots himself.