For the Quirk that has been mutated into this, see Eel.
After being kidnapped and modified by the Villain Factory, Teruo's original Eel Quirk evolved into a more powerful version known as Electric Eel. In addition to retaining the abilities of his previous Quirk like the slimy skin, Teruo can also discharge a surge of electricity.
Unlike his previous Quirk where he regained his human appearance, due to the modifications of the Villains Factory, even after the trigger injected into his body stopped to affect him, Teruo still retains the shape and appearance of a gigantic humanoid eel, only with a smaller size and a less intimidating appearance.
The Quirk still retains the weaknesses of its previous version. Teruo may pass out if he releases too strong an electric shock.