Pufferfish are enemies in Aqua Boy.
Pufferfish have two looks: one when they cannot see Aqua Boy, and one where they can. When Aqua Boy is far enough out of range from a pufferfish, its body is a long oval-shape and it is coloured pink. When a pufferfish does spot Aqua Boy, its body becomes more circular and its colour brightens to a lighter salmon shade.
Pufferfish often are positioned far away from Aqua Boy and remain in one place until they see him. When Aqua Boy gets close, they change colour and start to follow him around the screen. Aqua Boy can kill a pufferfish with his pistol, but once a pufferfish dies, it lets out a circle of bullets similar to that of the pink jellyfish. These bullets hurt Aqua Boy on contact.
If Aqua Boy chooses to not kill a pufferfish and instead, swims away from one, it will revert back to its normal form and continue to swim around the area until Aqua Boy gets close to it again.