5 piranha staring front

The Piranha Bark – The Warning Before the Bite?

Recently discovered is the fact the the Piranha barks. Much the same as other animals it  is a sound recognized by other fish that conveys meaning and warning in equal measure. So what is the Piranha trying to do when it barks.

In short, it’s been discovered that the Piranha emit 3 distinct sounds in relation to their situation. The first barking type is a confrontational bark, the second happens during fighting for food and the third is more of a croak when snapping at each other. More accurately they might be described as ‘barks’, ‘croaks’ and ‘clicks’.  They are used as combative warnings and during feeding or fighting. They appear to be related to an escalating level of combat. From a simple ‘leave me alone’, through a ‘I am thinking about biting you’ to ‘ now I am really, really angry’.

Do All Piranha Bark?

The Piranha barks more than they bite to misquote a phrase. They do so by contracting and expanding the swim bladder and grinding the teeth.

Researcher Eric Parmentier and his team simulated the Red-Bellied Piranha to contract and relax the swim bladder. It was noted that the swim bladder stopped vibrating as soon as the muscles stopped contracting. The Amazon waters are murky and very turbid and are very difficult to watch the behaviors of the fish, the fish can communicate through barks.

Scientists, to capture the different kinds of barking put hydrophones under the water in the Amazon basin. to capture the different noises made by many species of Piranha. It was found that the Piranha makes different noises throughout the day.

In total they identified three distinct types of barking, which are used by the Piranha for different circumstances.

They found all species of the Piranha bark as a means of communication. They further found that the Red-Bellied Piranha, which mostly lives in schools, require highly developed communication skills. The experiment was done on only 4 species in tanks but many more sounds were recorded, in the Amazon. The team believes all Piranha have the ability to bark.

The Amazon River has a very competitive niche where survival is key; barking is a means of communication when looking for food and warning others of predators in their environment. Barking for the Piranha is a means of survival for the species as and is a necessary skill to thrive in the murky waters of the Amazon basin.

a single red bellied piranha

Can You Identify Piranha by Their Bark?

Experiments on the acoustics produced by fish indicate that it is possible to identify different fish species using their noises and barks. Scientists have documented the sound of the Piranha fish in the murky Amazon waters, by catching the fish and recording the sound they produce by hydrophone recording and making a comparison.

During one of the experiments by Rodney Rountree, named “The Fish Listener” in 2012, a lot of fish were ‘auditioned’ by holding them underwater and recording their noises, the researchers were able to distinguish the noises made by different fish in the Amazon including the Piranha.

The ability to distinguish the sound of different Piranha fish can be extended to the wild by use of hydrophones attached to small boats to track piranha in their niche. Passive acoustic monitoring can be used to complement the traditional methods of surveying and capturing the fish.

It should be noted however that the sound of the bark would be disrupted by the hydrological water conditions and the size of the Piranha. Scientists however have discovered ways of identifying the fish with all the distractions that might disrupt the quality of the sound produced by the fish.

Why They Bark

The Piranha makes a barking sound primarily when they enter into a confrontation. The Amazon waters are murky and dark with large canopies covering the region. When they approach other fish, Piranha bark to mark their territories, by circling an opponent and making drum-like sounds.

They snap their jaws to produce a soft croaking sound when they feel threatened. Barking for the Piranha fish is a means of survival for the species in the murky waters of the Amazon Basin.

The Amazon River has more predators that could wipe away the fish, but through barks, the Piranha can warn other fish of danger in their area.

The Red-Bellied Piranha lives in shoals made of more than 20 fish that communicate acoustically especially when under attack. They can more efficiently respond to predators and overpower them.

During the feeding frenzy, the Piranha fish communicate by barking, creating an organized feeding pattern where the fish on the inner side of the school takes a bite of the prey and moves away to let those on the outer part of the shoal have a bite too,

Types of Piranha Bark

The three distinct sounds monitored were as follows.

Low grunts – like a bark

This is associated with chasing other fish away, like ‘get out of my face’. It is a visual face to face kind of communication that is made when facing another fish. Low grunts sound like croaking, and it is said to be one of the everyday communication skills by the fish. Low grunts is a means of creating dominance and intimidating another fish. The threat being you are annoying me, so go away or I will bite you.

A threat that most fish would, or at least should obey. It’s not an empty threat.

A low thud or drum-like sounds

Made by cycling and fighting another fish when they are fighting for food. The Piranha is known for being a ferocious creature who will fight for meat in the right conditions. They produce a low thud sound when fighting for food. They can even hurt themselves during this time.

During the dry spell when food is scarce in the Amazon region, you will hear Piranha barking as they are fighting for food in their habitat.

Gnashing sounds

The Piranha fish will rub their teeth together producing a gnashing sound. This is a warning for the fish that cross their territory. It’s much more combative than the initial bark. The bark is a warning.  If the other fish refuses to back down, they threaten them to move away with this gnashing sound..

They normally do this during the breeding season when they are protecting their young ones from attack by other fish that might come near their nests. Piranha are a territorial fish that protect their nests by chasing competitors and predators. Gnashing their teeth producing the biting sound is meant to scare the other fish away creating dominance.

Here are all three sounds that the Piranha makes:

What Effect Does Barking Have?

When Piranha bark, they chase away other fish within their territory especially during the breeding season they keep their young ones safe. Their predatory nature is characterized by stiff competition, and it is a means of chasing away other fish from their territory.  When they gnash their teeth they can chase away the most stubborn fish.

Their barking is a way of communicating acoustically in the murky waters of the Amazon; the Amazon is a dense region that has little light penetration. They can inform each other about looming danger in the territory, and they can fight any enemy may that approaches.

Piranha barking could prompt a feeding frenzy, especially during the dry season when food is scarce. In the Amazon region they fight to have a bite of dead meat or weak animals that might have fall into water indigenous to the Piranha fish.

Can You Locate Piranha by Their Bark?

Specific species of Piranha produce distinct noises which makes it easy to identify a specific fish species without capturing them.

By use of hydrophones that are attached to a boat in waters infested by Piranha, one can easily identify the fish by recording the sound they produce. It is possible to use acoustic means of locating the fish as complementary to the traditional method of identification.

The sound produced by the fish can change depending on the age of the fish, thus hindering ease of identifying the fish. Water conditions such as the presence of waves and other hydrological conditions affect the acoustics of the fish and the ability to identify specific Piranha fish within their habitat.

Piranha face on

If You Hear It Should You Be Worried?

Piranha fish are normally silent until they are approached by a threat; they start barking as a way of scaring away potential threats. It has also been observed that the fish also bark when fishermen catch them.

Presumably it’s an instinctive response to a perceived danger.

Barking is a means of warning enemies that may cross their path. Piranha barking is a normal thing and should not make you worried as they communicate with each other and other animals acoustically.

Chances are you won’t hear it through, as it’s an acoustic sound using water as the medium.


The Piranha are known to be ferocious biters, but their barking has caught the attention of fish experts who have ventured into studying the phenomenon. It was found that all Piranha bark as a means of communicating acoustically with Piranha and other fish in their habitat.

The murky waters of the Amazon provide less visibility, and the fish know each other by their barks. Predators in the region might pose a threat to the fish and through barking the Piranha can alert each other of looming danger.

When food is scarce in the Amazon, the Piranha barks during feeding frenzies as they are fighting to have a bite. The Red-Bellied Piranha is known to live in schools of fish; they survive by communicating through barks.

It is possible to identify different species of Piranha by their barks as different species of the fish produce different sounds. It could be possible to trace the fish by the use of sound and attaching hydrophones into the boats and listening to the sounds produced by the Piranha in their natural environment.

This might be the safest method of studying the fish unlike traditional methods of identifying the fish that involves capturing the fish physically.

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