They were called nothing (at least in English) because they were first described somewhere in the 18th century and they knew about electricity by then. Boring answer, but that's how it is.

In German they are called "Zitteraal" literally translated: tremble eel

Named after the people who were trembling on touch.

Spicy waternoodles

Prior to our understanding of electricity, many believed that electricty-producing animals were injecting some sort of venom.

wow your date can turn invisible, only a man of quality could attract such talent

Snappy snakes.

Eelectric

Magic longfish, obviously.

I was curious and started reading into it, apparently the ancient Egyptians used to call electric fish (as they hadn't discovered electric eels by that point) "Thunderer of the Nile"

"Eels"