Once upon a time, I made up a science fiction story.

A long time ago, an expedition found a small pond in a swamp. When they approached the small pond, the local Indians hired by the expedition were full of fear and refused to go any further.

The explorer found nothing unusual and walked into the small pond carelessly. At this moment, something terrible happened. One of the expedition members fell into the pond like a heavy blow, and the other two companions fell into the water inexplicably while saving him.

Later, after research by scientists, it was found that they fell into the water because they were attacked by freshwater electric eels.

The electric eel is a big fish, which looks like a snake. It can reach two meters in length and weigh more than twenty kilograms. On weekdays, he is motionless underwater. When it feels threatened, it will discharge and attack each other.

Later, people found that other fish can also discharge, such as torpedoes and catfish. South American electric eel can be said to be the "electric shock champion", which can generate 880 volts.