High-voltage catfish immune to their own shocks

Malapterurus beniensis may look like a harmless catfish lounging on the bottom of a tank, but these creatures are far from benign. Packing a powerful 300 V electric shock, the fish usually reserve their pyrotechnics for stunning prey. ‘We always wear thick rubber gloves when handling the fish’, chuckles Stefan Schuster from the University of Bayreuth, Germany, admitting that he and Georg Welzel once tried holding a small catfish without gloves: ‘The shock was surprisingly strong and felt like touching an electric fence’, he recalls. But how do electric catfish withstand their selfadministered shocks, which knock out the hearts and nervous systems of their victims? Do the catfish brace themselves to withstand their own electrical discharges, or are they somehow immune? Intrigued by the fish’s electrical resilience, Schuster and Welzel obtained two of the shocking creatures to find out how they and their victims deal with an electric jolt.