The average shock from an electric eel lasts about two-thousandths of a second. The pain isn’t searing — unlike, say, sticking your finger in a wall socket — but isn’t pleasant: a brief muscle contraction, then numbness.

For scientists who study the animal, the pain comes with the professional territory.

“I remember the first time I was shocked,” said Carlos David de Santana, an ichthyologist at the National Museum of Natural History in Washington, D.C., who recalled falling into the water and dropping his equipment. “I was scared.” Dr. de Santana has suffered several high-voltage attacks in his years studying electric eels, including one close to 400 volts.

He is the lead author of a study published Tuesday in Nature Communications describing the discovery of a new species of electrical eel, Electrophorus voltai. Named after Alessandro Volta, the Italian physicist who invented the battery, it can generate an electric shock as high as 860 volts, the strongest of any known animal. In the process, the researchers realized that what for centuries had been considered a single species of electric eel, Electrophorus electricus is actually three.

“It’s quite literally shocking, when you discover new diversity in such an eye-catching fish first described 250 years ago,” Dr. de Santana said. He became enamored of the serpentine freshwater fish during childhood summers on his grandparents’ farm, where he observed them while wading in the nearby Amazon River.