Cold Fish is a 2010 Japanese serial killer film directed by the controversial filmmaker Sion Sono (Love Exposure). It premiered at the 67th Venice International Film Festival and received the best screenplay award in the Fantastic Features section at Fantastic Fest 2010.
The film is about the quiet owner of a small tropical fish shop whose life and family are taken over by a fellow fish entrepreneur who happens to be a serial killer. Classified as a horror film with lots of graphic blood and gore (you have been warned!), this black comedy shows how the family descends into the depths of murder.
Apparently, 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.