The Incredible Mr. Limpet is a 1964 American live-action/animated comedy film directed by Arthur Lubin, produced by Warner Bros. and starring Don Knotts in the title role. The film tells the story of a mild-mannered bookkeeper named Henry Limpet who lives in Brooklyn with his wife Bessie. He is obsessed with fish and spends most of his free time studying marine life.
One day, while fishing on Coney Island, Henry falls into the water and is transformed into a fish. He discovers that he has the ability to talk to other fish and decides to use his new powers to help the US Navy in their fight against German submarines during World War II. Henry becomes an integral part of the Navy's efforts and he is finally able to prove his worth to his wife, who had been skeptical of his love for fish.
As a fish, Henry befriends a group of misfit fish, including a sarcastic Hermit Crab voiced by Jack Weston, a tough-talking Blowfish voiced by Charles Meredith, and a beautiful female fish named Ladyfish voiced by Elizabeth MacRae. Together, they help the Navy track down and destroy German submarines, with Henry using his powers to detect the presence of the U-boats and relaying the information to the Navy's sonar operators.
Eventually, the Navy's success leads to the defeat of the German navy, and Henry is hailed as a hero. He is given a medal and returns to his human form. The film ends with Henry and Bessie moving to a new home near the beach, where Henry can continue his study of marine life. The Incredible Mr. Limpet was a commercial success and remains a beloved classic to this day.