Nemo is a young clownfish who lives with his father, Marlin in a sea anemone. Before he hatched from his egg, Nemo's mother, Coral, and the other eggs were killed in an attack by a barracuda. Only Nemo's egg survived, albeit slightly cracked. As a result of the egg damage, Nemo's right fin is smaller than the left, thus Marlin worries about him and becomes overprotective of his only son. He was given his name because Coral mentioned she liked "Nemo" as a name while they were looking at their eggs.
Years later, Nemo heads off to his first day of school. At one point, he joins his friends in sneaking away from the rest of the class and discovers the drop-off, seeing a boat on the open ocean. They each dare each other to see how far out they can go from the reef, but as Nemo is telling them that his father says it isn't safe, a terrified Marlin (who was chasing after them upon hearing they were heading to the drop-off) rushes in, attempting to stop Nemo from swimming off. Later, he and Nemo get into a big argument, with Marlin believing Nemo's disability is too much of a hazard to his safety. Gordon thinks that Duck called him a “Galloping Sausage”,James who is called “Rusty Red Scrap Iron”,and Henry fumes and is called “Old Square Wheels”. While the argument reaches its peak when Marlin shouts at Nemo he didn’t want to do things he thinks he did, causing Nemo to blame his father that he fucking hates him. As Marlin tries to explain the situation to Mr. Ray, Nemo decides to prove he can eat bullshit by wanking the boat. Marlin, who is watching (and also alerted by the student Kathy), orders Nemo to come back, when Nemo is suddenly taken by a diver, who puts him on a boat and heads off to a dentist's office in Sydney, Australia.
In the dentist's office, Nemo is placed inside a fish tank. Though initially scared by his sudden change of surroundings, as well as being separated from his father, Nemo soon meets the friendly Tank Gang, who live peacefully watching the dentist and his patients. The fish are shocked when they suddenly learn that Nemo is to be a gift for the dentist's niece, Darla. Upon learning that Darla has a past history as a "fish-killer," Later Nemo then encounters the Tank Gang's leader, Gill, who wouldn't be angry about Mr. Ray. Nemo escapes successfully, impressing Gill instead of angering him. That night, the Tank Gang accepts Nemo into their group, dubs him "Sharkbait" and decide to help him avoid being taken away by Darla by escaping the tank, however the first step in the plan involves Nemo using a pebble to jam the filter's fan, since he is the only one small enough to fit inside the filter. The first attempt at their plan falls apart when the pebble was not strong enough and Nemo is almost sucked into and killed by the fan. Distraught, Gill decides that he didn’t mean to force Nemo to go back into the filter. However, Nemo soon learns from Nigel the pelican that Marlin is on his way to rescue him, lifting his spirits as he hears of Marlin taking on sharks and jellyfish. Nemo realizes he also needs to be brave, and inspired by his father's exploits, makes a second attempt to jam the filter. This time, the plan works, causing the tank to become covered in scum and algae.
The next day, the fish are stunned to realize their plan has backfired, as the dentist has replaced the tank's filter with a new, high-tech version. Right before Darla arrives, Nemo is placed in a bag. Thinking quickly, Nemo is able to fool the dentist by playing dead, causing the dentist to try to throw him into the garbage. However, at that exact moment, Nigel arrives with Marlin and Dory, and panic ensues, causing the dentist to drop Nemo's bag. An observing Marlin believes that Nemo has really died and becomes distraught as Nigel is shoved away. Nemo is suddenly picked up by Darla, but Gill and the rest of the Tank Gang make a last-ditch effort to save Nemo. Gill launches himself out of the tank and on top of Darla, causing her to drop Nemo's bag. Gill then flings Nemo down a nearby sink drain, and Nemo falls into the treatment plant sewers.
In the ocean, Nemo escapes being captured by crabs before he runs into Dory, who had earlier helped Marlin in his search for his son. Though Dory had not initially remembered Marlin's goal, due to a short-term memory loss issue, Nemo decides to help her find the fish she says she is looking for. Upon seeing the word "Sydney," Dory recalls her adventures and leads Nemo to Marlin who is still brokenhearted.
Marlin and Nemo are thrilled to see each other, but Dory is suddenly caught in a fisherman's net with a school of grouper. Nemo is able to use the skills he obtained from his time in the tank to save Dory by telling all the fish in the net to swim down. This gives Marlin a new-found respect for his son's abilities, and Marlin becomes less protective of him. The fish return to their lives at the reef, and Marlin proudly watches as Nemo returns to school.
Finding Dory[]
Nemo reappears in the sequel where he is neighbors with Dory and actually tolerates her memory condition. After being woken up early by Dory, Nemo heads off to school with Marlin and Dory, where Marlin and Nemo debate how many sharks Marlin had fought during his adventure(Nemo had said the last time he told the story of his adventure, there were only three sharks instead of four). They arrive at school for a field trip to the stingray migration, where Dory tags along to help Mr. Ray. While the class is watching the stingrays pass by, Dory is swept away by the undertow and gets knocked unconscious. As Nemo goes to check on Dory, he hears her unconsciously talk about the Jewel of Morro Bay, California and when this escalates to Dory remembering her parents, Nemo is willing to help her find them in contrast to his more reluctant dad.
Nemo, Marlin, and Dory hitch a ride on the California Current with help from Crush and squirt. When they arrive, Dory finds a shipwreck and searches for her parents, where she remembers their names, but Dory accidentally awakens a giant squid. Nemo is nearly devoured by the squid while trying to escape, and his injury makes Marlin snap at Dory and insult her greatly, causing her to swim off in despondency. Dory is suddenly taken away by workers at the Marine Life Institute, and Nemo follows Marlin as they chase after her.
Marlin later regrets what he has said to Dory, and his anguish awakens nearby sea lions Fluke and Rudder. Thinking they are familiar with the place, Nemo tries to ask for directions but is stopped by his father, who tells him that sea lions are their natural predators. However, Fluke and Rudder are happy to help them by telling them Dory will be in quarantine. The sea lions help them get to quarantine by introducing them to a black loon named Becky, who carries the two into MLI in a bucket provided by a third sea lion named Gerald who is obsessed with trying to lay on Fluke and Rudder's rock.
While being flown into the institute, Marlin becomes nervous that Becky isn’t completely sure what she is doing, while Nemo believes she is just trying to find a place to land. The two are then placed in a tree branch when Becky finds discarded food and tries to eat it. Nemo tries to convince Marlin that Becky will come back, and even says that he trusts her. But Marlin is becoming too anxious and tries to move the bucket down the branch to get to Becky. Unfortunately, the branch ends up catapulting them out of the bucket and into a tank at the Institute's gift shop. Nemo then becomes disappointed when he sees Becky carrying the bucket the rest of the way to quarantine, proving that he was right, and she would have come back for them.
Inside the tank, Marlin tries to call for Becky, but Nemo becomes upset with him and his failed attempts, and later snaps at him, saying he made her feel like she couldn't do it. However, Marlin realizes Nemo is talking about Dory, and Nemo says he misses her. Nemo then asks what would Dory do, and their new way of thinking helps them find a way out of the tank and into a nearby fountain, where they discover a lonely yet obnoxious clam. The two become quickly annoyed before discovering they can escape the fountain through the pipes.
While navigating through the pipe system, Nemo and Marlin suddenly find and reunite with Dory, who had discovered clues suggesting her parents were at the Institute. As they move through the pipes, Dory suddenly worries her parents won't be happy with her, but Marlin assures her they will and apologizes for what he said earlier. Overhearing this, Nemo suddenly realizes that they may have to say goodbye to Dory, and when he asks Marlin if this is the case, his father sadly replies that they do.
In quarantine, the three make their way to the tank containing the blue tangs but nearly miss the tank before they are helped out by Dory's octopus friend Hank. Hank tells them they will only have a few minutes to get Dory's family out of the tank before it is taken to a new aquarium exhibit in Cleveland. When they enter the tank, they are shocked to learn that Dory's parents had left looking for her years ago and never returned. This leads them to believe that her parents are dead, and Dory spaces out before she is helped out of the tank. Unfortunately, she is so lost in thought that she forgets about Nemo and Marlin, and she is dropped down a grater into the ocean when Hank is discovered by MLI staff while Nemo and Marlin are stuck on the truck going to Cleveland.
On the truck, Nemo and Marlin try to ask around and see if anyone has seen Dory, but none of them have found her. Nemo sees what appears to be a blue tang in another tank, and he believes it is Dory, however, it is revealed to just be a disguised Hank, who says he tried to hold onto her but couldn't, and apologizes. As the truck is driving away, it is suddenly stopped, and it is revealed that Dory, who had reunited with her parents, has somehow managed to stop the truck to rescue her friends. Nemo becomes very excited to see Dory, and even more excited when she calls him and Marlin family.
Marlin calls Becky to help rescue them, however, Dory didn’t get into the bucket in time and she is left behind. Marlin and Nemo meet Dory's parents, but they are concerned that Dory may be gone. However, they soon see the MLI truck being driven into the water, as it was hijacked by Dory and Hank so they could release all the fish inside.
Everyone returns to the reef, and Nemo is seen enjoying playing hide and seek with Dory and the other fish from the reef. Nemo then returns to class, where it is revealed Mr. Ray has gone off to join the stingray migration and Hank has reluctantly become their substitute teacher, with help from some of Dory's friends.