Toxis is an extremely rare toxic Slug. It has lime green skin, a small nub on the back of its head, and the same antenae type as a Jellyish. When transformed they look like an eel that spits acid. A possible reason for being so rare could be that, to an unexperienced slugslinger they could be dismissed as being only a Flopper, but catching one could also be difficult due to the fact they can secrete acid, which would make them hard to handle in the first place.
- In the slugisode Know Your Ghouls!, Trixie's computer showed a Toxis slug on it.
- it was seen in The Slugout probably as an error.
Its main attacks are related to acid, such as secreting acid as a defense mechanism, in which case attempting to eat one would be dangerous. (Which Trixie implies when saying that a Cave Troll would rather eat one than admit Mechanic's defeat.)