Piranhas use sound to deter barking like rivals rather than attack them, say scientists.
Using underwater microphones, the team at the University of Liege in Belgium, recorded the sounds made by fish when confronted.
In an article published in the Journal of Experimental Biology, said the team has identified three types of sounds, each one containing a "message" specific.
Lead researcher Eric Parmentier studied sounds and communication methods used by many species of fish and believes that such knowledge can help man live better with marine life.
He explained, for example, that many species use sound to attract a mate. In this case, the sound becomes an important indicator that the species is reproducing.
"If we can understand what behaviors are associated with certain sounds we can hear the ocean and explain to fishermen: 'Now is not the best time to start fishing.'"
Parmentier knew that piranhas make sounds, but wanted to understand why.
The team put a hydrophone - an underwater microphone - within a tank of piranhas and filmed the interactions between fish.
Three types of sounds were recorded: the first, like a bark, was used when the fish measured forces confronting each other face to face, without physical aggression.
The second type, a percussive beat, was used when the fish were chasing each other. A third sound, a softer quack, too percussive, was used when the piranhas biting each other.
The assaults took place, in general, when they fought the fish for food.
During most of the time, however, the fish swam peacefully, without conflict and without sounds. Only hours after patient observations, the researchers were able to capture the behavior.
"For animals, it is less costly (in terms of energy) to do a lot of noise and impress others than to fight," said Parmentier.
Piranhas, like many other fish "noisy" produce the sounds vibrate their swim bladders - gas-filled organ that helps fish regulate their buoyancy.
The team also studied the muscles, moving at high speeds, are responsible for these vibrations.
"This muscle contracts and relaxes 150 times per second to vibrate the swim bladder," Parmentier said the BBC.
The team now hopes to study at home piranhas on the Amazon River, to learn more about their acoustic repertoire.