Researchers at the University of Liege in Belgium say the notorious tropical fish use sounds to communicate and often try to intimidate rather than attack rivals, the BBC reported Thursday.
Researcher Eric Parmentier and his colleagues put a hydrophone, an underwater microphone, into a tank of piranhas as they interacted and recorded three distinct sounds made by the fish, each with a seeming "message."
The first was a "bark" the fish made when "displaying" to each other, face to face but not fighting.
The piranhas produced a drum-like percussive effect when they chased one another and a softer croak when they finally resorted to biting each other in rare physical fights over food, researchers said.
"For animals, it's less expensive [in terms of energy] to make a lot of noise and impress the other guys, rather than fight," Parmentier said.