The Red Koi Fish is what you use to summon the Mighty Dragon in the Year of the Dragon. When the player shoots red koi fish out of the slingshot, the Mighty Dragon comes and defeats all the pigs in the area. When the player touches an eye symbol next to the pause sign, all the birds still disintegrate and a red koi fish hops on the slingshot.
Additionally, achieving Total Destruction of a level earns the player a red koi fish on the level selection screen. This functionality aligns with the concept of feathers earned with the Mighty Eagle in other episodes.