Electric fish can use the generation and detection of electrical signals as a sort of navigational sonar. They may also use their electrical signals for communication. In addition, two fish can also deliver a powerful electrical shock: the electric "eel" of South America, and the electric catfish of Africa. The James R. Record Aquarium exhibited both of these fish, in addition to several weakly electric fish.

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Electric Eel (head) Electric Catfish (head)
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Electric Eel: note the short body and long tail. In this fish the muscles of the long tail generate the electrical shock. Electric Catfish: note the longer body. In this fish the muscles of the anterior half of the body generate the electrical shock.

The Aba-Aba, a weakly electrical fish. Note that the dorsal fin is expanded in this fish.
The Black Ghost Fish, another weakly electrical fish, has an extended ventral fin.

This Asian Knifefish also has an extended ventral fin.

Electrical fish can read the electrical signals around them best when the body is kept relatively rigid, so the job of moving the fish through the water has been transferred to an expanded dorsal or ventral fin. What do you think is different about the electric catfish?

All of the fish on this page, except the electric catfish, are members of the Knifefish family, which contains more than 100 species.

More information from the University of Arizona Tree of Life entry on Gymnotiform (knife) fish.