Deadweed is the Halloween-themed episode of Slugterra, and it is the eighth episode of season one. It first aired on October 19th, 2012 on Disney XD.
Eli doesn't believe in ghosts -- until he enters Deadweed cavern! But it turns out Eli's first instinct was right. What lurks inside Deadweed is far more evil than ghosts, its El Diablus Nacho, after a supply of the dangerous Dark Water that Dr. Blakk uses to turn innocent slugs into Ghouls.
The episode starts with the Shane gang in the fog and mist as they get nearer to Deadweed Cavern. Eli senses no danger and goes inside the cavern but only Pronto is the one who does not want to go in there. They go on a little and Trixie is shooting a video film of it. For a flash she sees someone go form the front of her camera. Then the gang sees the ghosts and the men who had touched the dark water and had become so, but that had been revealed later. They start to run but the door closes and they are stuck in Deadweed. They go down a vast cavern and see a huge amount of black water that Dr. Blakk used to ghoul Slugs. Just then the Slugterran Express arrives and El Diablos Nacho is seen taking the dark water with them through filling containers. Just then Shane Gang make their entries and Eli starts with a Rammstone but Nacho dodges it and showes a new ghoul which Eli thinks to be is Frightgeist but Trixie tell him that it is the ghouled Nightgiest. Nacho shoots the Slug and it hits Eli. He runs away with Burpy on his foot persuading him to stop. On the other side the ghosts come and threaten Nacho for going away. Eli's about to go when he sees a ghastly form which reduces into a friendly frightgiest Slug. Eli takes the help of ghosts to stop Nacho. Kord and Trixie are trying to stop the pool of dark water. Nacho says that he's not frightened by any of the ghosts. Just then the ghosts go back and Eli comes out saying he will he shoots the frightgiest. Nacho runs away to the Slugterran Express and runs away with stock of black water he has got. Kord shuts down the pump and all the ghosts turn back into normal men. The last scene is Nacho pleading to Blakk to forgive him. He says that not to worry, there's stock for a month, and the camera zooms out to show thousands of containers filled with dark water.
- Featured Slug - Frightgeist.
- This is the first episode to be a Holiday themed episode.
- The scene when a Hop Rock is turned into a Hop Jack in a Ghouling Machine is similar to the one in "The Slugout".
- In one scene where the Shane Gang is fighting the ghosts, Eli shoots a Rammstone twice in quick succession, though he only has one Rammstone in his arsenal.
- When the Shane Gang are using the biohazard suit Trixie's eyes are blue.