|“||Nemo is a curious and impressionable six-year-old boy who lives alone with his overprotective, single-parent father, Marlin. Having led a sheltered life, Nemo brims with the excitement of starting school and finally seeing the wonders of the Great Barrier Reef. Despite being born with a withered fin, Nemo yearns for adventure, and as fate takes him far from home, he learns he is capable of doing great things... like his father.||”|
In the film, he is Marlin's son, and is the sole survivor of the barracuda attack, after his mother Coral and his many brothers and sisters died. Damage to his egg left one of Nemo's fins smaller than the other, affecting his ability to swim. On his first day of school, when he is captured by divers, one of whom is a dentist, they take him to Sydney, Australia. Nemo eventually finds himself in a marine aquarium in the dentist's office, where he meets a group of marine animals known as "The Tank Gang". Nemo participates in a plot to escape where they break the filtration system by throwing a rock into the fan blade to get the tank dirty, thus forcing the dentist to clean the tank. The first attempt is botched, as Nemo has not adjusted the rock into the blades tightly enough. However, after learning that his dad is trying to look for him, he tries again and is successful this time. Unfortunately, while he may have succeeded in breaking the filtration system, that has not stopped the tank from being cleaned without the gang being removed, as the dentist has replaced the old version with an advanced cleaner. After Darla arrives and Nemo is placed into the bag, Nemo plays dead in order to get the Dentist to flush him down the toilet, but the plan nearly backfires when the dentist decides to throw him out in the trash can instead. His attempt also has had the unintended consequence of Nigel, Marlin and Dory believing that he has truly died. He ultimately succeeds with help from Gill, who fires himself out of the tank and catapults Nemo onto the dentist's sink leading to the drain, which leads back to the ocean. Nemo then encounters Dory, who initially doesn't remember who he is until seeing the word "Sydney" on one of the pipes, to which she aids Nemo in finding his dad, including interrogating one of the crabs into revealing where he went. Nemo and his father are happily reunited, but it is cut short when a Fishermen's net captures a school of fish, and Dory has also become trapped in the same net. Nemo rushes over to save Dory from the net by telling the other fish to swim down together. All the trapped fish pull down on the net, and manage to break themselves free, although the effort leaves Nemo injured. Nemo then reconciles with his father, telling him that he doesn't hate him anymore, to which Marlin apologizes to his son for being overprotective.
Sometime later, Nemo and Marlin have a racing match from their home to the place where Mr. Ray is waiting and Nemo beats his father in the match. Before Nemo leaves with his classmates, he asks Mr. Ray to hold for a moment, and he swims over to his father to tell him that he loves him. After Marlin tells his son that he loves him as well, he lets go of Nemo, allowing him to "go have an adventure."
Nemo gets lost again in "The Seas With Nemo & Friends" at Epcot in Walt Disney World.
Nemo returns in the sequel Finding Dory.
- In Monsters, Inc., Nemo appears as one of the toys that Boo gives to Sulley after she returns to her room. He also appears on the wall of the Trailer Son and Mom's trailer when Sulley and Mike throw Randall through the door.
- A Nemo sticker is seen on Andy's toy chest in Toy Story 3.
- Nemo also makes a quick cameo in Brother Bear during the scene where Kenai disrupts the salmon fishing.
- Nemo's name could very well be a reference to Captain Nemo from Jules Verne's novel 20,000 Leagues Under the Sea and Disney's 1954 film adaptation.
- Nemo, in turn, is actually Latin for "no one." In the aforementioned novel, Captain Nemo was so called since nobody ever knows what his real name is, if he ever had one.
- Nemo's friend Sandy Plankton could be a reference to Nickelodeon's SpongeBob SquarePants, as "Sandy" and "Plankton" are names of characters from that show.