- Directors: Rob Letterman, Vicky Jenson, Bibo Bergeron
- Producers: Jeffrey Katzenberg
- Writers: Rob Letterman
- Genres: Animation, Comedy, Family
- Actors: Will Smith, Jack Black, Robert De Niro, Angelina Jolie, Martin Scorsese, Ziggy Marley, Doug E Doug, Lenny Venito
The story begins with an underachieving fish named Oscar (Will Smith), who is fantasizing about being rich and famous… while making his way to work as a tongue scrubber at the local Whale Wash. Soon after arriving he is called to the office of his boss, Sykes (Martin Scorsese), to discuss the fact that he owes “five thousand clams” and has to pay it back by the next day. After explaining this to his best friend Angie (RenÃ©e Zellweger), she offers him a chance to pay back the money by pawning an heirloom pink pearl. Oscar brings the money to the race track to meet Sykes, but becomes distracted by his wishes of grandeur and places it all on a long-shot bet. Such a large bet is noticed nearby by a beautiful fish named Lola (Angelina Jolie), who flagrantly flirts with Oscar until quickly discovering the truth. Sykes is furious that Oscar bet the money but nonetheless agrees to see how the race turns out. Moments before their “horse” crosses the finish line he trips and falls. The race is lost and Oscar is set to be surreptitiously killed.
Meanwhile, on another side of the ocean, a family of criminally-inclined sharks has a problem with one of their sons, Lenny (Jack Black). Lenny refuses to act the part of a killer and wishes to not have to live up to those expectations. Finally his father, Don Lino (Robert De Niro), loses patience and orders Lenny’s more savage brother, Frankie (Michael Imperioli) to show Lenny the ropes. As the two sharks set out to go in accordance with their father’s wishes, Frankie spots the scene where Oscar is being electrocuted by Ernie and Bernie (Doug E. Doug & Ziggy Marley), Sykes’ two Jamaican jellyfish thugs, and sends Lenny off to attack. The jellyfish spot Lenny and swim off, leaving Oscar alone with him. Lenny frees Oscar but fails to trick Frankie, who becomes annoyed and charges at Oscar until an unknown anchor falls and kills him. Lenny flees, overcome with grief and guilt. As no one saw the deed done and Oscar was seen near the body, everyone thinks he did it, and Oscar sees this as the chance to both redeem himself and receive his fame.
Oscar buys some Valentine’s Day gifts for Angie, but before he can present them to her, he finds that Don Lino has abducted Angie in order to force a meeting. Lenny comes along, now disguised as a dolphin named Sebastian. They arrive at the meeting to find Lola next to Don Lino, while Angie is bound and gagged and presented to Don Lino on a plate, who prepares to eat her if Oscar doesn’t comply. Oscar just laughs and “Sebastian” lunges forward to scoop Angie into his mouth, giving Oscar dominance over the sharks. However, he spends too much time threatening the sharks and doesn’t realize how much pain Lenny is in, and Angie is regurgitated onto the table. Don Lino suddenly realizes it’s Lenny and proceeds to chase Oscar through the reef, but Oscar heads for the whale wash and ends up trapping both sharks. Given an ovation by the other fish, Oscar confesses that he is not a “Sharkslayer” and that it was an anchor that had killed Frankie. He then strongly urges Don Lino not to prejudge people before he knows them properly and to not make the mistake he made in prejudging his wealth, so Don Lino and Lenny reconcile. Oscar forsakes all the wealth he has acquired, makes peace with the sharks, becomes manager of the Whale Wash (now frequented by sharks), and begins dating Angie.