An Electric Eel thriving. Though it's called Eel, it is not, as it is a Knifefish.
The Electric Eel (Electrophorus electricus) is a species of electric fish, or more specifically, a species of Knifefish from the family Gymnotidae and the genus Electrophorus. This fish lives all over South America and is also confirmed to sometimes thrive in mud puddles during dry season. This fish feeds on smaller fish and mammals, and uses its electricity to stun the prey. A full grown specimen is usually about 2 meters long and 40 or so pounds. An Eel this size can easily stop a humans heart, as it delivers 500 volts of electricity.
Many deaths have occured involving this fish, including 1 incident in which a group of cowboys where all killed at once while swimming, by this fish.