Electric eel (Electrophorus electricus) is thick and long, up to about 250 cm long. They mainly live in the Amazon river basin of South America. They are hide in the daytime and come out at night, and mainly prey on small fish. It is not a species of eel and is more closely related to the catfish in biological classification. It has a smooth, scaleless body surface, no dorsal and pelvic fins, and a particularly long anal fin, which is the main organ for swimming. Its output voltage ranges from 300 to 800 volts. Our household voltage is usually 220 volts. Within 3 to 6 meters of water, people are often knocked unconscious by touching the electricity emitted by the eel. So it has the water “high voltage line” which is extremely dangerous. Scientists have created a battery based on their unique anatomy.