Philip is the dentist who takes Nemo and adds him to the collection in his fish tank at his office. He is Darla's uncle and is supposedly going to offer Nemo to her as her new pet fish. He isn't technically a villain; he only caught Nemo because he thought he would die in the ocean, and when he sees Nigel by his office fish tank, he probably thinks the pelican wants to eat the fish, so he shoos him away.
On the day Dr. Sherman enters the office to take care of patient Davey Reynolds, he finds his tank dirty. He asks Barbara to leave the time before his earliest appointment open so that he can clean the tank prior to Darla's arrival. Rather than putting his fish into bags and clean the tank himself like what he used to do, he installs an AquaScum 2003 into his tank to let the device do the job, thus sabotaging any chance of his fish escaping the office. Coincidentally, it is also the day when Darla is coming to the office, so he prepares his gift for his niece by scooping Nemo out of the tank with a net, but Nemo, with help from the Tank Gang, swims down, causing the dentist to drop the net. The dentist then scoops Nemo out with a plastic bag, and to prevent Nemo from escaping, he puts the bag into a plastic storage bin. After Darla arrives at the office, Nemo plays dead to try to have the dentist flush him down the toilet. When the dentist finds Nemo in that state, he assumes that Nemo has died, but instead of flushing him down the toilet, the dentist instead heads for the trash to dispose Nemo. However, he is interrupted by Darla's scream because of Nigel the Pelican invading the office.
In the ensuing melee, Dr. Sherman, still holding Nemo's bag, tries to grab Nigel, but bumps into the pelican, causing him to drop the bag onto the tray of dentist's tools. Dr. Sherman pushes the pelican out of the office and closes the window. Darla picks up Nemo's bag and starts shaking it, prompting Gill to have his gang fire him out of the tank and land onto Darla's head, causing Darla to drop the bag onto the same tray, and the bag pops, freeing Nemo. Dr. Sherman turns to notice the animals going mad, and hits his head into a scope suspending from the ceiling, which knocks him to the floor. While the dentist is knocked down, Gill jumps onto the dentist's mirror to catapult Nemo onto the sink, letting the juvenile clownfish escape the office through the drain, through the sewers, and back into the ocean. After recovering, Dr. Sherman finds Gill on his tray and puts him back into the tank.
At the end of the film, he complains to Barbara that his new AquaScum 2003 (which has a lifetime guarantee) is broken, much to his dismay. This prompts him to take the fish out, put them into bags, and clean the tank himself. But, much to his shock, the fish have all escaped.