At the same time, the film had a quote that "all drains lead back to the ocean" (Nemo escapes from the aquarium by going down a sink drain, ending up in the sea). Since water typically undergoes treatment before leading to the ocean, the JWC Environmental company quipped that a more realistic title for the movie might be "Grinding Nemo". However, in Sydney, much of the sewer system does pass directly to outfall pipes deep offshore, without a high level of treatment (although pumping and some filtering occur). Additionally, according to the DVD, there was a cut sequence with Nemo going through a treatment plant's mechanisms before ending up in the ocean pipes. However, in the final product, logos for "Sydney Water Treatment" are featured prominently along the path to the ocean, implying that Nemo did pass through some water treatment.
The Australian Tourism Commission (ATC) launched several marketing campaigns in China and the USA in order to improve tourism in Australia, many of them using "Finding Nemo" clips. Queensland also used "Finding Nemo" to draw tourists to promote its state for vacationers.
On the 3-D re-release, Lisa Schwarzbaum of Entertainment Weekly wrote that its emotional power was deepened by "the dimensionality of the oceanic deep" where "the spatial mysteries of watery currents and floating worlds are exactly where 3-D explorers were born to boldly go."
The 3-D re-release also prompted a retrospective on the film then nine years after its initial release. Stephen Whitty of the Newark Star-Ledger described it as "A genuinely funny and touching film that, in less than a decade, has established itself as a timeless classic," with Roger Moore of the McClatchy-Tribune News Service calling the movie "the gold standard against which all other modern animated films are measured."
"Finding Nemo" was released on DVD and VHS on November 4, 2003. The film was also released on DVD in a "Gold Edition", which came with a "Finding Nemo" stuffed toy character. The film had a home video release on both Blu-ray and Blu-ray 3D on December 4, 2012, with both a 3-disc and a 5-disc set.
The inspiration for Nemo was made up of multiple experiences. The idea goes back to when director Andrew Stanton was a child, when he loved going to the dentist to see the fish tank, assuming that the fish were from the ocean and wanted to go home. In 1992 shortly after his son was born, he and his family took a trip to Six Flags Discovery Kingdom (which was called Marine World at the time). There he saw the shark tube and various exhibits he felt that the underwater world could be done beautifully in computer animation. Later, in 1997 he took his son for a walk in the park, but found that he was over protecting him constantly and lost an opportunity to have any "father-son experiences" on that day. In an interview with "National Geographic" magazine, he stated that the idea for the characters of Marlin and Nemo came from a photograph of two clownfish peeking out of an anemone:"It was so arresting. I had no idea what kind of fish they were, but I couldn't take my eyes off them. And as an entertainer, the fact that they were called clownfish—it was perfect. There's almost nothing more appealing than these little fish that want to play peekaboo with you." Also, clownfish are very colourful, but don't tend to come out of an anemone very often, and for a character who has to go on a dangerous journey, Stanton felt a clownfish was the perfect kind of fish for the character.
Pre-production of the film took place in early 1997. Stanton began writing the screenplay during the post-production of "A Bug's Life". As such, it began production with a complete screenplay, something that co-director Lee Unkrich called "very unusual for an animated film." The artists took scuba diving lessons so they could go and study the coral reef. The idea for the initiation sequence came from a story conference between Andrew Stanton and Bob Peterson while driving to record the actors. Ellen DeGeneres was cast after Stanton was watching "Ellen" with his wife and seeing Ellen "change the subject five times before finishing one sentence" as Stanton recalled. There was a pelican character known as Gerald (who in the final film ends up swallowing and choking on Marlin and Dory) who was originally a friend of Nigel. They were going to play against each other as Nigel being neat fastidious while Gerald being scruffy and sloppy. However the filmmakers could not find an appropriate scene for them that didn't slow the pace of the picture down, so Gerald's character was minimized.
Stanton himself provided the voice of Crush the sea turtle. Stanton originally did the voice for the film's story reel, and assumed they would find an actor later. When Stanton's performance was popular in test screenings, Stanton decided to keep his performance in the film. Stanton recorded all his dialogue while lying on a sofa in co-director Lee Unkrich's office.
Crush's son Squirt was voiced by Nicholas Bird, the young son of fellow Pixar director Brad Bird. According to Stanton, the elder Bird was playing a tape recording of his young son around the Pixar studios one day. Stanton felt the voice was "this generation's Thumper" and immediately cast Nicholas.
Megan Mullally revealed that she was originally doing a voice in the film. According to Mullally, the producers were dissatisfied to learn that the voice of her character Karen Walker on the television show "Will & Grace" was not her natural speaking voice. The producers hired her anyway, and then strongly encouraged her to use her Karen Walker voice for the role. When Mullally refused, she was dismissed.
The film was dedicated to Glenn McQueen, a Pixar animator who died of melanoma in October 2002.
Finding Nemo shares many plot elements with "Pierrot the Clownfish", a children's book published in 2002, but allegedly conceived in 1995. The author, Franck Le Calvez, sued Disney for infringement of his intellectual rights. The judge ruled against him, citing the color differences between Pierrot and Nemo.
To ensure that the movements of the fish in the film were believable the animators essentially took a crash course in fish biology and oceanography. They visited aquariums, went diving in Hawaii and received in-house lectures from an ichthyologist.
"Finding Nemo" earned $380,673,009 in North America, and $540,900,000 in other countries, for a worldwide total of $921,573,009. It is the second highest-grossing film of 2003, behind "". In North America, outside North America, and worldwide, it was the highest-grossing Pixar film, up until 2010 when "Toy Story 3" surpassed it.
"Finding Nemo" set an opening-weekend record for an animated feature, making $70,251,710 (first surpassed by "Shrek 2"). It became the highest-grossing animated film in North America ($339.7 million), outside North America ($528.2 million) and worldwide ($867.9 million), in all three occasions outgrossing "The Lion King". In North America, it was surpassed by both "Shrek 2" in 2004, and "Toy Story 3" in 2010. After the re-release of "The Lion King" in 2011, it stands as the fourth highest-grossing animated film in these regions. Outside North America, it was surpassed by "", "Toy Story 3", and "". Worldwide, it now ranks third among animated films.
The film had impressive box office runs in many international markets. In Japan, its highest-grossing market after North America, it grossed $102.4 million becoming the highest-grossing Western animated film until it was out-grossed by "Toy Story 3" ($126.7 million). Following in biggest grosses are the UK, Ireland and Malta, where it grossed £37.2 million ($67.1 million), France and the Maghreb region ($64.8 million), Germany ($53.9 million), and Spain ($29.5 million).