Probably stinging or lightning eels or something.

Zappy eels

In German it is "Zitteraal" meaning trembling eel.

Evolution

Taxonomy

When the species now defined as Electrophorus electricus was described by Carl Linnaeus in 1766, based on early field research by Europeans in South America and specimens sent back to Europe for study,[3][4][5] he used the name Gymnotus electricus, placing it in the same genus as Gymnotus carapo (the banded knifefish).[6][7][8] He noted that the fish is from the rivers of Surinam, that it causes painful shocks, and that it had small pits around the head.[6][b]

In 1864, Theodore Gill moved the electric eel to its own genus, Electrophorus.[7] The name is from the Greek ήλεκτρον ("ḗlektron", amber, a substance able to hold static electricity), and φέρω ("phérō", I carry), giving the meaning "electricity bearer".[1][10] In 1872, Gill decided that the electric eel was sufficiently distinct to have its own family, Electrophoridae.[11] In 1998, Albert and Campos-da-Paz lumped the Electrophorus genus with the family Gymnotidae, alongside Gymnotus,[12] as did Ferraris and colleagues in 2017.[8][2]

In 2019, C. David de Santana and colleagues divided E. electricus into three species based on DNA divergence, ecology and habitat, anatomy and physiology, and electrical ability. The three species are E. electricus (now in a narrower sense than before), and the two new species E. voltai and E. varii.[13]