Piranhas communicate with sound, say researchers

Despite a nasty reputation, piranhas seem to bark more often than bite.

Scientists have discovered that the fearsome fish use sounds to communicate - often intimidating their rivals rather than attacking.

With underwater microphones, scientists recorded the sounds the fish made when they confronted one another.
They reported in the Journal of Experimental Biology that each of these three sounds appeared to contain a different "message".

Lead researcher Eric Parmentier, from the University of Liege, Belgium, has studied sound production and communication in a wide variety of fish species, including the charismatic clownfish and the spectacularly ugly toad fish.

He already knew that piranhas made sounds, but wanted to understand why.

Many fish use noises to attract a mate, so the sounds are an important indicator that the fish are reproducing.

"Eventually, if we understand the behaviour that's associated with the sounds, we might be able to listen to the sea and explain to fishermen: 'Now's not the best time to start fishing'."

Dr Parmentier and his colleagues put a hydrophone - an underwater microphone - into a tank of piranhas in their lab and filmed the fish as they interacted.

They recorded three distinct sounds. The first was a bark that the fish produced when they "displayed" to each other - confronting one another face to face but not fighting.
Read on...