Purple fish are enemies in Aqua Boy
Purple fish have a round body and triangular tipped fins. They are purple on the top half of their body, and red on the bottom half. A small, red, round fin is also visible. Their eyes are single black pixels, and they have small round teeth in their large mouths.
Purple fish appear in a line of six, travelling across some passageways. When Aqua Boy enters a passageway that purple fish are in, they will start to swim across the screen in a single direction. At most times, this is opposite the direction of Aqua Boy's travel. As the fish swim, they move their mouths up and down and alternate vertical direction while swimming, creating a wave-like motion.
Aqua Boy can kill purple fish with a single blast of his pistol, but since they move faster than other enemies in the game, killing the purple fish may take more than one shot. When the fish die, they sometimes leave behind a shard of charge or a heart of health. They deal half a heart of damage to Aqua Boy on Normal difficulty and a full heart of damage on Hard.