It is about a man named Henry Limpet who turns into a talking fish and helps the U.S. Navy locate and destroy Nazi submarines.

The story begins in 1963, where George Stickle (a naval officer) and Admiral Harlock discuss how porpoises in the ocean are displaying unique characteristics and suspect that a former top-secret asset, Henry Limpet, may be teaching the creatures these abilities.

The fish Limpet, complete with his signature pince-nez spectacles, discovers a new-found ability during some of his initial misadventures: a powerful underwater roar, his "thrum".

He helps the Navy locate Nazi U-boats by signaling with his "thrum", and plays a large part in the Allied victory in the Battle of the Atlantic.

In the film's coda, back in 1963, George and the Admiral travel out to sea to contact Limpet about whether he is training the porpoises.

The cruiser USS Los Angeles was offered for use at the time of pre-production planning, but was decommissioned late 1963, before principal filming began.

The animated sequences were handled by Warner Bros. Cartoons under the supervision of Robert McKimson, and it was the final project for the studio prior to its temporary closure in spring 1963, as well as one of the few non-Looney Tunes productions they worked on.

"[12] Diabolique magazine called it "overlong and clearly budget challenged but full of charm, and is reminiscent of the Francis movies... an extremely likable story.

The project entered development in 1996 when Steve Rudnick and Leo Benvenuti were hired as writers for a remake of The Incredible Mr.

[14] By 1997, Jim Carrey entered negotiations to star in the title role,[15] and was confirmed in February 1998 with Steve Oedekerk hired as the writer and director.

Roughly $10 million was spent on animation tests to digitally map Carrey's motion-captured human face onto a fish's body, which produced disastrous results.

[25] That same month, Femke Wolting and Tommy Pallotta had begun working on the design and animation on the project while Galifianakis would reportedly play the lead character.

[26] On July 8, 2014, it was announced that Jon Hamm, Danny McBride, Sarah Silverman, Kevin Hart, Josh Gad, Keegan-Michael Key, and Jordan Peele had entered talks for various roles in the film.