Yukio Murata, a patron at the supermarket, persuades the manager to drop the matter and invites Nobuyuki to visit his own, larger tropical fish shop.

The film is loosely based on the exploits of two Tokyo serial killers, Sekine Gen and Hiroko Kazama, a husband and wife duo who owned a pet shop and murdered at least four people.

[1] Following Alien vs Ninja and Mutant Girls Squad, Cold Fish is the third film to be released by Nikkatsu's Sushi Typhoon, their gore-themed series.

[2] Director and writer Sion Sono was influenced by Japanese crime cases while developing Cold Fish, specifically about an actual killing spree committed by a dog kennel owner in the 1990s (the story of the film involves a family of three that becomes entangled in a string of ongoing murders perpetrated by a tropical fish salesman in Shizuoka Prefecture).

[7] Radio Times gave the film three out of five stars, praising the acting from Denden, Fukikoshi and Kurosawa and Shinya Kimura's photography and Takashi Matsuzuka's production design, which made up for "some overindulgent directorial moments".