What is the name of Nemo's father?

Nemo’s father is Marlin.

Marlin is an orange clownfish who lives with Nemo on the Great Barrier Reef. At the start of Finding Nemo, Marlin and his mate Coral are waiting for their eggs to hatch when a barracuda attacks. Coral and nearly all the eggs are lost, leaving one surviving egg. Marlin names the hatchling Nemo and becomes intensely protective of him.

That protectiveness drives the story. When Nemo is captured by divers and taken to a dentist’s fish tank in Sydney, Marlin crosses the ocean to find him. Along the way, he travels with Dory, meets sharks and sea turtles, and gradually learns that protecting Nemo also means trusting him to face challenges.

Gill is a Moorish idol in the aquarium, Crush is a sea turtle, and Dory is Marlin’s traveling companion—not Nemo’s parent. Marlin’s relationship with Nemo is central to the film’s emotional arc: the adventure changes him from an anxious, fearful father into one who recognizes his son’s growing independence.