Hello, Frank Indiviglio here.
With their ridiculously long “noses” (actually an extended jaw), secretive ways and unique feeding strategies, the elephant-nosed fishes have long been aquarium favorites. All of the 200+ species discharge electrical pulses from specially-modified muscle cells near the tail.
The most commonly kept species, Peter’s elephant nose, has been shown to vary the strength, frequency and duration of these discharges. Doing so helps this nocturnal fish to navigate and hunt in the turbid West African rivers it inhabits.
Using Electricity to Choose a Mate
Recently, researchers at Germany’s Potsdam University have shown that a related species, Campylomormyrus compressirostris, identifies potential mates by the characteristics of their electrical discharges.
In laboratory tests, gravid females responded to the signals of males of their own species, but ignored those of a closely related fish that shares their natural habitat. In this way, they are able to locate a mate of the proper species, even when surrounded by similar fishes in murky water at night.
It is theorized that Peter’s elephant nose also uses electricity as a form of communication and mate recognition. Certainly, watching them avoid obstacles and locate buried blackworms in an aquarium at night, it is easy to see how completely they rely upon their electric-generating system.
Keeping Elephant-Nosed Fishes
Although very popular, elephant-nosed fishes require special care and rarely do well in community aquariums. I recently set up an exhibit housing a group along with some other of their interesting West African neighbors – butterfly fishes, giant filter-feeding shrimp and dwarf clawed frogs. Please look for an article on this exhibit and their general care soon.
Please Note: The “trunk-less” fish pictured with the elephant noses is not the victim of an unfortunate accident but rather a related species, the baby whale or stoneroller, Pollimyrus isidori. They are also quite interesting and do, if you have an active imagination, somewhat resemble (very!) small whales. I’ll address them in the article mentioned above.
Belgium’s Africamuseum has posted an interesting article on the Peter’s elephant nose (Note: the photo appears to be of a deceased fish…they are much more attractive than pictured here!): http://www.africamuseum.be/museum/treasures/gnathonemus%20petersii
Please write in with your comments and questions. Thanks, until next time, Frank Indiviglio.