The main ducks in the game are Swampy Ducks, which there are three of in each level. Water is needed to fill up the ducks, whereas Poison Water, Toxic Ooze, and Mud will kill the duck. Getting all three ducks in a level is referred to as tri-ducking. If the player tri-ducks all levels in a chapter, the player will earn a tri-ducked duck, which will display on the title screen in Swampy's bathtub.
Ducks are also needed to unlock chapters. The player will to earn a certain amount of ducks to unlock a chapter. The player can also buy the Locksmith Duck to unlock a chapter (or all chapters) immediately.
There's a Pirate Duck in The Lost Levels. Swampy Ducks appear also in The Lost Levels. Swampy is taking a shower to get all clean, and to do that, play the lost levels like, The 10 Days of Swampy, Hearts & Crafts, and The Days of Summer.
In Cranky's Story, there are purple ducks that are called Cranky Ducks that are used by Cranky. They are similar to Swampy Ducks, however they need poison water to fill up. They'll be killed by regular water, ooze and mud.
There's a magical version called the Mystery Duck that only appears in the Mystery Duck mode. In the Mystery Duck levels, instead of the regular three Swampy Ducks, Mystery Duck can either spawn himself, a Mega Duck, or ten Ducklings. To beat the level, the player needs to fill the duck(s) with water while also getting the water to Swampy's shower and completing the level.