Listening to Electric Fish

"At your local tropical fish store, you can find a particularly wonderful creature called an Elephant Nose fish, or more properly, Gnathonemus petersii, a member of the Mormyrid family.

Besides the obvious visual interest of the animal, there is another fascinating aspect to it -- it emits pulses of electricity into the water, with which it locates food, other fish, and potential mates.

It is easy to listen in on these electrical signals with simple inexpensive equipment, such as a piezoelectric earphone, or a small amplifier." You can find more info and samples at scitoys.com