|MLA Citation:||Bloomfield, Louis A. "Question 500"|
How Everything Works 19 Jan 2018. 19 Jan 2018 <http://howeverythingworks.org/print1.php?QNum=500>.
You're correct that current is an important issue here, since even household static electricity can separate enough positive charge from negative charge to reach thousands of volts. However, static electricity can reach very high voltages because there is no current flow to deplete the separated charge. In the case of an electric eel in water, the water conducts current well enough that the eel must continue to separate charge to maintain the 600-volt potential difference between its ends. I'm not sure how much current flows through the fresh water in this situation, but I would guess that it's at least 1 ampere and possibly more. That means that the eel is moving a considerable amount of charge each second and using in excess of 600 watts of power. If the eel were a salt-water fish, it wouldn't be able to reach a 600-volt potential difference at all because salt water conducts current far to well and an enormous current would flow in that case.