My living room 90-gallon fish tank with five elephant-nose fish (Mormyridae) from the Congo River. The two with long snouts are Campylomormyrus numenius, the one with a short, steeply angled snout and patterning visible on the side is a Campylomormyrus elephas, the more uniform brownish one with a shorter snout at a shallow angle is a Campylomormyrus tamandua, the smallest individual with an intermediate snout is a C. compressirostris. When they pass by the electrode dangling in the tank near the heater you can hear the fish's electric organ discharge (EOD). The C. numenius have very low-frequency pulses, while the other three species are high-frequency. The EODs are digitized and fed into my computer via an Edirol FA-66 external sound card. Picture via a Logitech C920 camera. The water is yellowish because I condition it with peat to soften it.