Piranha II: The Spawning

In an interview, James Cameron said this movie gets better halfway through when seen at the drive-in with a six pack of beer.

Although this is the first official directing credit for James Cameron, most of the work was actually performed by Ovidio G. Assonitis, the film's producer and prolific film-maker. Assonitis had made a deal with a small label at Warner Bros. for a budget of $500,000 to produce the movie, provided that an American was credited as director. After considering Miller Drake as director but finding him unsuitable, he gave the job to Cameron after being impressed by his special effects on Galaxy of Terror (1981); but what he really wanted was a first-timer who he could easily side-step in order to take over as director, something he had already done on Beyond the Door (1974) and Madhouse (1981). According to "Dreaming Aloud," a biography of James Cameron by Christopher Heard, and "The Futurist" by Rebecca Keegan, Cameron worked on the film's special effects, re-wrote the script, created storyboards, did location scouting and actually filmed for four days. However, Assonitis called most of the shots, continuously questioned Cameron's decisions, did not allow him to watch his own footage, and finally fired him on the fifth day of shooting, reportedly because Cameron's footage wouldn't cut together. Later, Cameron was able to convince Assonitis to show him a rough cut of the film, which was horrible, but not because there was anything wrong with his footage: Assonitis had simply manipulated the situation to re-write half the movie (adding nudity that wasn't in the script originally). Cameron then broke into the editing room every night for weeks, and cut his own version. Unfortunately, Assonitis found out and re-cut it again. The most widely distributed version of the film that is available on DVD is Assonitis' version, although Cameron was later allowed to create a director's cut that saw a limited release in some markets.

James Cameron had come to Rome to see the film's post-production, but he had spent his entire advance salary on the plane ticket. With no money for food, he just snatched leftovers and rolls from dinner trays in his hotel. Due to the exhaustion and malnutrition, he grew ill with fever, and had a nightmare about a metallic torso emerging from an explosion, and dragging itself over the floor with kitchen knives, which gave him the idea for The Terminator (1984).

James Cameron reused the flying piranha effects in Aliens (1986) for the face-huggers.

In an interview, James Cameron jokingly said, "I believe 'The Spawning' was the finest flying piranha movie ever made."