Seen in “Hydra”.
The Hydra Eel is an advanced 3 headed version of the Eel from "Electric City". When the Eel's corpse was recovered by the Paradigm Corporation, they used their genetic engineering to create a mutated albino clone. Vera Ronstadt detonated the creature's holding cell, letting it loose on the city. Like its genetic template, the creature attacked with extremely large electrical blasts; this included a supersized blast that combined the energy of all 3 heads into a single charged blast.
It also had a remarkable regenerative ability, as seen when it was able to fully regrow 2 of its 3 heads in a matter of seconds. The research team's intention was to use the Hydra's bio-electricity to reactivate Big Fau, which they achieved by extending a lightning rod and siphoning off the Hydra's electricity when its superblast bounced off the Big O's Plasma Gimmick. Roger Smith and Big O killed it with the Plasma Gimmick, by expanding it towards the Hydra.