An electric fish is a fish that can make electric fields. Fishes that can generate such fields are said to be electrogenic, those that can detect them are called electroreceptive. Most electrogenic fish are also electroreceptive. Many fish, for example sharks, rays, and catfishes are electroreceptive. They cannot generate electric fields though, and are therefore not classified as electric fish. Most bony fish are neither electrogenic nor electroreceptive.
Strongly and weakly electric fish[change | change source]
Electrogenic fish have a special organ that can generate electricity. This organ is usually called an electric organ. It is usually near the tail of the fish. It is made from specialised muscle or nerve cells. When the organ produces electricity that is released this is called electric organ discharge (or EOD for short).
Based on the strength of the EOD, the electrogenic fish can be classified into two types:
- Strongly electric fish: Their discharge is so strong they can stun (and capture) prey with it. Examples for such fish are the Electric eel (which is a knifefish, not a true eel), electric catfishes, or electric rays
- Weakly electric fish: Their discharge is not strong enough to stun prey with it; rather, they use the electricity to locate objects, to navigate, or to communicate with other electric fish. Examples for weakly electric fish are Peters' elephantnose fish or Black ghost knifefish.
In total, there are 348 known species of electric fish, in about 56 genera. The only known species that lives in salt water are the electric rays, with 23 species.