They were only seen as a small group of refugees in Episode II: The Samurai Called Jack, as the leader was requesting Aku for immigration to earth, as their home world had been drained of its water. The Shogun of Sorrow proceeds to reveal that it was he himself that had stripped the planet of its water for his own world's purposes. A young Vadaquian steps up and expresses his anger to Aku, only to be sent to The Pit of Hate to learn respect.
The species currently inhabits the oceans of Earth, on the condition of constructing statues of Aku once each month and raising them to the surface.
After Aku's destruction in the past, all the atrocities Aku has done to their planet were undone. So, they presumably live there in harmony, free from Aku's evil.
- The Vadaquians share some parallels with another species, the Mud Aliens;
- Both species were allowed to live on Earth by Aku.
- Both species create Aku-shaped monuments to honor him.
- Both species end up annoying Aku and are dismissed from his presence due to it,
- Both species appear in the second episode of the season they appear in: the Vadaquians in Season 1 Episode II, and the Mud Aliens in Season 5 Episode XCIII.