Sadie is a butterfly tang fish who has appeared with Fred and Tom and makes many cameo appearances throughout the series, starting with the episode called "Ripped Pants."
She is a light yellow female fish with light olive-green lips, black eyes, and light faded blue fins. She has blue hands and legs and wears a floral-printed dress that is white and red.
Sadie is the ex-wife of Tom and they have been shown together in numerous episodes, such as "Fear of a Krabby Patty."
In "Evil Spatula," it is revealed that she and Tom are the parents of a purple daughter and green baby. Sadie is also the ex-wife of Nat Peterson and they have been shown together in many episodes, such as "Goo Goo Gas."