The film received extremely positive reviews and won the Academy Award for Best Animated Feature. It was the second highest-grossing film of 2003, earning a total of $921 million worldwide.  Finding Nemo is also the best-selling DVD of all time, with over 40 million copies sold as of 2006,  and was the highest-grossing G-rated film of all time before Pixar's own Toy Story 3 overtook it. It is also the 23rd highest-grossing film of all time, as well as the 3rd highest-grossing animated film. In 2008, the American Film Institute named it the tenth greatest animated film ever made during their Top 10.

Plot
Two ocellaris clownfish, Marlin and his wife Coral are admiring their new home in the Great Barrier Reef and their clutch of eggs that are due to hatch in a few days. Suddenly, an Australian barracuda attacks them, leaving Marlin unconscious. Marlin wakes up to find out the barracuda has eaten Coral and all but one of her eggs. Marlin names this egg Nemo, a name that Coral liked.

The film then moves on to Nemo's first day of school. Nemo has a tiny right fin, due to a minor injury to his egg from the barracuda attack, which limits his swimming ability. After Marlin embarrasses Nemo during a school field trip, Nemo disobeys his father and sneaks away from the reef towards a boat, resulting in him being captured by scuba divers. As the boat sails away, one of the divers accidentally knocks his diving mask into the water.

While unsuccessfully attempting to save Nemo, Marlin meets Dory, a good-hearted and optimistic regal blue tang with short-term memory loss. While meeting three sharks on a fish-free diet at a meeting, Bruce, a great white shark; Anchor, a scalloped hammerhead; and Chum, a shortfin mako shark, Marlin discovers the diver's mask that was dropped from the boat and notices an address written on it. However, when he argues with Dory and accidentally gives her a nosebleed, the scent of blood causes Bruce to lose control of himself and attempt to eat Marlin and Dory. The two escape from Bruce but the mask falls into a trench in the deep sea. During a hazardous struggle with an anglerfish in the trench, Dory realizes she is able to read the address written on the mask, which leads to Sydney, Australia, and manages to remember it. After receiving directions to Sydney from a large school of moonfish, Marlin and Dory accidentally run into a bloom of jellyfish that nearly sting them to death; Marlin falls exhausted after the risky escape and wakes up to see a surf-cultured sea turtle named Crush, who takes Dory and him on the East Australian Current. In the current, Marlin reluctantly shares the details of his journey with a group of young sea turtles; his story spreads rapidly across the ocean through word of mouth and eventually finds Nemo in Sydney.

Meanwhile, Nemo's captor - P. Sherman, a dentist - places him into a fish tank in his office on Sydney Harbour. There, Nemo meets a group of aquarium fish called the "Tank Gang", led by a crafty and ambitious moorish idol named Gill. The "Tank Gang" includes Bloat, a puffer fish; Bubbles, a yellow tang; Peach, a ochre starfish; Gurgle, a royal gramma; Jacques, a pacific cleaner shrimp; and Deb, a Blacktailed Humbug. The fish are frightened to learn that the dentist plans to give Nemo to his niece, Darla. She is infamous for killing a goldfish given to her previously by constantly shaking the bag. In order to avoid this fate, Gill gives Nemo a role in an escape plan, which involves jamming the tank's filter and forcing the dentist to remove the fish from the tank to clean it manually. The fish would be placed in plastic bags, at which point they would roll out the window and into the harbor. After a friendly Brown Pelican named Nigel visits with news of Marlin's adventure, Nemo succeeds in jamming the filter, but the plan backfires when the dentist installs a new high-tech filter.

Upon leaving the East Australian Current, Marlin and Dory become lost in the blooms of plankton and krill and are engulfed by a blue whale. Inside the whale's immense mouth, Marlin desperately tries to escape while Dory communicates with it in whale-speak. In response, the whale carries them to Port Jackson and expels them through his blowhole. They are met by Nigel, who recognizes Marlin from the stories he has heard and rescues him and Dory from a flock of hungry gulls by scooping them into his beak and taking them to the dentist's office. By this time, Darla has arrived and the dentist is prepared to give Nemo to her. Nemo tries to play dead in hopes of saving himself, and, at the same time, Nigel arrives. Marlin sees Nemo and mistakes this act for the actual death of his son. Gill helps Nemo escape into a drain through a sink after a chaotic struggle.

Overcome with despair, Marlin leaves Dory and begins to swim back home. Dory then loses her memory and becomes confused, but meets Nemo, who has reached the ocean through an underwater drainpipe. Dory's memory is restored after she reads the word "Sydney" on a nearby drainpipe and, remembering her journey, she guides Nemo to Marlin. After the two joyfully reunite, Dory is caught in a fishing net with a school of grouper. Nemo bravely enters the net and directs the group to swim downward to break the net, reminiscent of a similar scenario that occurred in the fish tank earlier. The fish, including Dory, succeed in breaking the net and escape. After some days, Nemo leaves for school once more and Marlin who is no longer overprotective or doubtful of his son's safety, proudly watches Nemo swim away into the distance.

Back at the dentist's office, the high-tech filter breaks down and The Tank Gang have escaped into the harbor. However, they realize that they are confined to the bags of water that the dentist put them into when cleaning the tank.

Production
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 do not 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 did not 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.

Reception
A costume advertisement for the Idaho Aquarium in February 2013.

Finding Nemo has achieved overwhelming critical acclaim. It currently holds a 99% fresh rating at Rotten Tomatoes  and an average of 89 on Metacritic.  Roger Ebert gave the film four stars, calling it "one of those rare movies where I wanted to sit in the front row and let the images wash out to the edges of my field of vision."  Broadway star Nathan Lane who was the voice of Timon the meerkat in The Lion King, said Finding Nemo was his favorite animated film.

The film's use of clownfish prompted mass purchase of the animal as pets in the United States, even though the movie portrayed the use of fish as pets negatively and suggested that saltwater aquariums are notably tricky and expensive to maintain.  The demand for clownfish was supplied by large-scale harvesting of tropical fish in regions like Vanuatu.

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.

Tourism in Australia strongly increased during the summer and autumn of 2003, with many tourists wanting to swim off the coast of Eastern Australia to "find Nemo".  The Australian Tourism Commission (ATC) launched several marketing campaigns in China and the USA in order to improve tourism in Australia, many of them utilising 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."

Box office
Finding Nemo earned $380,843,261 in North America, and $540,900,000 in other countries, for a worldwide total of $921,743,261.  It is the second highest-grossing film of 2003, behind The Lord of the Rings: The Return of the King.  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 out-grossing 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 Ice Age: Dawn of the Dinosaurs, Toy Story 3, and Ice Age: Continental Drift. 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).

Accolades
Main article: List of Pixar awards and nominations: Finding Nemo

Finding Nemo won the Academy Award and Saturn Award for Best Animated Film. It also won the award for best Animated Film at the Kansas City Film Critics Circle Awards, the Las Vegas Film Critics Society Awards, the National Board of Review Awards, the Online Film Critics Society Awards, and the Toronto Film Critics Association Awards.

The film received many awards, including:
Kids Choice Awards for Favorite Movie and Favorite Voice from an Animated Movie, Ellen DeGeneres.
Saturn Award for Best Supporting Actress, Ellen DeGeneres

Finding Nemo was also nominated for:
Two Chicago Film Critics Association Awards for Best Picture and Best Supporting Actress, Ellen DeGeneres
A Golden Globe Award for Best Motion Picture – Musical or Comedy
Two MTV Movie Awards for Best Movie and Best Comedic Performance, Ellen DeGeneres

In June 2008, the American Film Institute revealed its "Ten top Ten", the best ten films in ten "classic" American film genres, after polling over 1,500 people from the creative community. Finding Nemo was acknowledged as the 10th best film in the animation genre.   It was the most recently released film among all ten lists, and one of only three movies made after the year 2000, the others being The Lord of the Rings: The Fellowship of the Ring and Shrek.

American Film Institute recognition:
AFI's 100 Years...100 Movies (10th Anniversary Edition) – Nominated
AFI's 10 Top 10 – #10 Animated film