Piranha (IMAGE) Louisiana State University Caption LSU researchers and collaborators found some surprising relationships for the Characiformes, an order of ray-finned fishes that includes tetras and piranhas. Credit Prosanta Chakrabarty, LSU Usage Restrictions None License Licensed 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.