Electric eel

The electric eel, touches or gets very close to the prey with its head. The return path is through the water which acts like a return path to the rest of its body, especially the back end. A complete path is required. The power from the eel is so strong, that it can stun a horse! The discharge is at about 600 Volts, at about 10 to 20 ma. The shock from the electric eel when under water, can easily kill a man. After discharging, the electric eel requires a number of hours to recharge again.

There is also the electric cat fish, and electric ray fish.

Some details about the electric eel, and how it works.