Madame Hagfish is an old hagfish and the former secondary antagonist of the episode "The Curse of the Hex."
She has a lavender eel-like body like a real hagfish. She has teal fins on the tip of her tail and her upper arm. Clothing-wise, she wears a tattered dark burgundy shawl tied in the front. On her upper body she has a bunch of warts throughout her whole face, pinkish-purple dried out lips, wrinkled under-eyes, a pair of glasses lined with a gold rim with gold hoop earrings, and has light blue lenses. Her hair is styled curled up into bunches and cone shaped on either side of her head. She also wears a light green cloth bandana on top of her head.
She is nice to people who help her, but is not to those who don't.
She enters the Krusty Krab and spews slime in front of Squidward. The latter refuses to give her a Krabby Patty since these type of burgers have gone up in cost since she had been there before and Madame Hagfish only uses a couple of shells as money. She later puts a curse on the restaurant. A curse shows no sign of any customers, plates falling without big thumps, and dollars on fire and teared apart showing it catches on fire again. She has a lot of slime on her body that way she can suffocate her prey like regular hagfishes.
SpongeBob and Mr. Krabs both go to Madame Hagfish's magic wheel wagon house to tell her to put the curse away. To put said curse away of the Krusty Krab, SpongeBob and Mr. Krabs are sent to get her the golden doubloon that was stolen by the Giant Golden Eel. SpongeBob and Mr. Krabs then enter the Golden Eel's cave and they see the eel sleeping. SpongeBob slips on its leftover pudding/green slime and the eel wakes up. The Giant Golden Eel grabs Mr. Krabs and starts strangling him. Sponge touches the eel softly and it lets go of Mr. Krabs and is touched again by SpongeBob and spits out the doubloon.
SpongeBob and Mr. Krabs return and give the doubloon to Madame Hagfish and she puts it in the washing machine to clean her clothes. It shows that the Krusty Krab curse was a "closed" sign that was standing outside for a long time. The "curse" is lifted and customers visit the Krusty Krab. However, the Giant Golden Eel appears again and goes on a rampage.