What is the name of the pufferfish in the tank?

The pufferfish in the tank is named Bloat.

Bloat is one of the seven members of the Tank Gang, the group of aquatic animals living in Philip Sherman’s dentist-office aquarium. He is portrayed as a porcupine pufferfish, and his most recognizable gag is inflating himself when frightened, startled, or upset.

Bloat is easy to confuse with the other tank residents because Finding Nemo gives each character a distinctive personality rather than repeatedly emphasizing species. Bubbles is the yellow tang obsessed with the tank’s bubbling treasure chest, while Peach is the starfish attached to the glass. Gill, Deb, Gurgle, and Jacques complete the original Tank Gang.

The tank’s residents are not simply background decoration: they are trying to escape captivity before Darla, the dentist’s niece, receives Nemo as a gift. Bloat participates in their plans, including the attempt to stop the tank filter and force the aquarium to become dirty enough for cleaning. After Nemo’s escape, Bloat and the rest of the gang eventually leave the office tank in sealed plastic bags.