Voidfish

The Voidfish is a mysterious giant jellyfish who works for the Bureau of Balance. It consumes memories for all beings, except those who have been inoculated by drinking from its tank (it might be Voidfish pee).

Powers and Special Abilities
The Voidfish eats memories, completely deleting knowledge from the minds of anyone who has not been inoculated.

Rites of Remembrance
When a Bureau of Balance employee dies in the line of duty, their name is fed to the Voidfish, who consumes all living memories of that individual (except from the minds of those inoculated to the effects of the Voidfish.

In Episode 41, we get some clarity around the full extent of the powers of the Voidfish during Boyland’s Rites of Remembrance. The Voidfish has an ability to erase information, but also the ability to implant whatever someone needs to write their own story about why the information fed to the Voidfish is missing from the realm. When Boyland is fed to the Voidfish, for instance, the can make it so the inscription on Boyland’s chair is unreadable, so it’s like it’s “for a family friend who… they also can’t remember.”

The Voidfish lights up whenever someone not inoculated tries to remember information the Voidfish has consumed. In particular, when Boyland is consumed, the Voidfish lights up like the Northern Lights, bright with the memories of his comically large family

The Voidfish eats the memories. It’s possible for someone to tell the Voidfish about something one wanted an inoculated person to forget (example: debts unpaid, farts in embarrassing places), and the Voidfish would be more than happy to eat those memories for you. However, the Voidfish cannot Eternal Sunshine of the Spotless Mind anyone who has been inoculated (no matter how much Merle wants to not remember Boyland).