Piranhas have been found to bark by a team of biologists from the University of Liège, Belgium.
The scientists used a hydrophone (an underwater microphone) to monitor sounds emitted by captive red-bellied piranhas. Thus far they have identified three distinct noises made by the flesh-eating fish.
While fighting for food, piranhas make a short percussive drum-like sound; when snapping at each other they produce a softer croaking noise; and when preparing for a confrontation, they bark.
It is possible piranhas might make an additional sound when feeling particularly amorous, but due to the difficultly of breeding the fish in captivity, this is yet to be determined.Read more at University of Liège