Electric eels are fish capable of generating an electric field. Tuna fish 1.8 patch recording of resting electric organ discharge of Brachyhypopomus bennetti. An electric fish is any fish that can generate electric fields. A fish that can generate electric fields is said to be electrogenic while a fish that has the ability to detect electric fields is said to be electroreceptive.
Video of a complete electric organ discharge. The electric field potential is represented on a sagittal across the modelled fish. Hot tones represent positive potential values, while cold tones represent negative electric potentials. The black line indicates the points where the potentials are zero. Electric fish produce their electrical fields from a specialized structure called an electric organ. Strongly electric fish are fish with an electric organ discharge that is powerful enough to stun prey or be used for defense. Typical examples are the electric eel, the electric catfishes, and electric rays.
Strongly electric marine fish gives low voltage, high current electric discharges. In salt water, a small voltage can drive a large current limited by the internal resistance of the electric organ. Hence, the electric organ consists of many electrocytes in parallel. Freshwater fish have high voltage, low current discharges. In freshwater, the power is limited by the voltage needed to drive the current through the large resistance of the medium.