Electric Knifefish in Observation Tank (VIDEO) Johns Hopkins University This video is under embargo. Please login to access this video. Caption An observation tank illuminated by infrared shows electric knifefish behavior with the lights on (top) and lights off (bottom). Credit Johns Hopkins University. Usage Restrictions none License Original content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.