The Mon Cala eel, alternatively called the Mon Calamari eel or electric eel, was a predatory eel species inhabiting the oceans of Mon Cala. Their slippery nature was well-known.
The debut of the Mon Cala eel occurred in "Prisoners," specifically episode three of Star Wars: The Clone Wars' fourth season, which aired on September 23, 2011. The names Mon Cala eel and electric eel were initially used to describe them in the episode's guide on StarWars.com. The 2015 novel Dark Disciple was the first to refer to them as Mon Calamari eels.
George Lucas asked for the eels to be used as a type of prison, to illustrate an alternative method of restraining Jedi. Prior to the "Prisoners" episode, The Clone Wars had only depicted them being contained by an energy field. Artist Carlos Sanchez was responsible for the eels' design.