The Red-Bellied Piranha is the Piranha that everyone thinks of when they think of Piranhas. It’s a fascinating fish that makes appearances in Hollywood movies, and as such is the most popular for home aquariums. But how much of its mystique is true?

In short, the Red-Bellied Piranha, also just known as the Red Piranha if a freshwater fish primarily found in the Amazon basin. The are actually omnivores, with a typical diet of insects, fruits, worms, crustaceans and fish. They are scavengers and foragers, schooling with 20 fish or more for defense against the natural predators, such as the river dolphin, storks, egrets and caimans. It is most common around the Paraguay, Paraná and Essequibo basins and is a non migratory species. Like all Piranha, they can only survive in warm water. It is considered one of the more aggressive Piranha, but attacks on humans are rare. They perform the much fabled ‘Piranha frenzy attack’ on already dead animals that drift down the river systems.

The Classification Of Red-Bellied Piranha

This, the most famous of the Piranhas, belongs to the family, Serrasalmidae. It a medium sized fish, and within the Serrasalmidae family, is further classified from the genus Pygocentrus.

The are actually classified as omnivores, yet is also known to be carnivorous in nature.

Identifying a Red-Bellied Piranha

As the name suggests, the fish has red undersides. The cheeks, chin, and the belly are a lovely deep red. The rest of the Red-Bellied Piranhas body is grey with tones of brown flecks of silver and gold. Black spots are, however, found behind the gills.

The color of their bodies and tints vary with the age and gender of the fish. They range from clear to reddish. According to fish experts, females have darker bellies than the male fish. The Red-Bellied Piranha has powerful jaws with a single row of interlocking tightly packed triangular-shaped teeth.

The Red-Bellied Piranha can grow up to about 15 inches, but are typically six to eight inches as an average. Adult Red-Bellied Piranha weighs about 1.4kgs although they can grow to weigh up to 3.2kgs.

The Red-Bellied Piranha has a lifespan of 10 years or more.

Where in the Amazon?

The Red-Bellied Piranha is found in the fresh waters rivers throughout the Amazon basin in South America. They prefer the densely populated regions of the neotropical rivers of Brazil, Argentina, Bolivia, Ecuador, Colombia, Guyana, Peru, Paraguay, Uruguay, and Venezuela.

They prefer the warm fresh waters of major rivers which include the Amazon, Paraguay, Essequibo and Parana basins and other small river systems found in the Amazon region. Although they live in warm water above 25 degrees Celsius, they can also survive, but not reproduce,  in cold water as low as 10 degrees Celsius.

The fish is mainly found in the white waters but are occasionally found in black waters and clear waters of the oxbow lakes and floodplains found in the Amazon basin.

Typical Red-Bellied Piranha Diet.

The Red-Bellied Piranha plays a major role in the environment, as they act as predators and scavengers. Their typical diet include worms, fish, crustaceans, and insects during feeding frenzies piranhas shoal can eat large animals like egrets and capybara.

The Red-Bellied fish is known to be ferrous and dangerous, but they are scavengers and foragers that feed on almost anything that comes their way. They can, and do, bite off fins of other fish that pass by. Small Red-Bellied Piranha fish will search for food during the day, and the adults forage at dawn.

They lurk behind the plants so that they can ambush their prey.

In zoos and aquariums the Red-Bellied Piranha feed on gelatin diet which contains a mixture of greens, proteins and other micronutrients found in a gelatin base. They also eat smelt, shrimp, herring and earthworms.

Humans and other large animals are not part of their regular diet. Many local fisherman around the basin wade in the water without fear of attack. They will only really attack a large animal if it threatens the hatching eggs, there is scarce food or it is scavenging an already dead animal.

Red-Bellied Piranha Senses

This Piranha has an advanced sense of smell; they can locate their prey easily and can smell blood in the water over a few miles. It’s said they can detect a drop of blood for every 200 litres of water, and trace it to its source.

Their bodies have a special line of sensors down the side of their bellies that picks up vibrations in the water and water pressure, as well as currents and movements. The Red-Bellied Piranha is one of the few species that have this sensitivity along their lateral line systems.

Communications in Red- Bellied Piranha

The Red-Bellied Piranha show signs of acoustic communications. Their shoals are very organized. Under attack, the fish on the outer part of the shoal communicate with the ones at the middle section of the shoal, which will react calmly to attack, and coordinate with the rest of the school..

The fish also bark when under threats through the production of drumming sound by contracting and relaxing the muscles of the swim bladder.

They also grind their teeth as a means of threatening fish that could attack them.

This behaviour is to ward of potential predators.

Reproduction

The reproduction of Red-Bellied Piranha is still ongoing. They are able to reproduce when they are one year old. They also form ‘mating pairs’.

The females will lay eggs in the mud, where a nest has been made, and the male Piranha then fertilizes  them.

The eggs will hatch after two to three days depending on the conditions that prevail in their natural habitat. The young fry of Red-Bellied Piranha will hide behind river or lake plants to avoid predators.

The Red-Bellied Piranha will guard their young ones against any threat in their environment.

They have two annual breeding season which depends on the water fluctuations, such as flooding, overly cold temperatures, and other hydrological conditions. Overly strong currents are a disaster.

The fish only reproduce when the conditions are right, the females will lose the red color, and their abdomens enlarge as they get ready to lay eggs, of which there can be 1000 or more laid.

The Shoals of Red-Bellied Piranha

The Red- Bellied Piranha will travel in shoals. Initially, this was thought as a means for the fish to attack their prey. The idea being a large number of small fish make a bigger predator.

However, this is now thought to be a defense mechanism against themselves being prey. The Piranha has to be alert to egrets, storks, herons, river dolphins, alligators and caimans, all of which see the Red-Bellied Piranha as a tasty meal.

Shoals of Piranha build their nests in margins of flooded areas and travel in shoals to reduce the exposing themselves to attacks. They react to the smell of blood and will often feed in shoals during feeding frenzies.

Shoals, also known as a school, typically number 20 or so.

Is it the Most Aggressive Piranha?

The Red-Bellied Piranha is one of the most aggressive of the Piranha species. Their jaws are very strong and have such a strong bite.

The fish is omnivorous but will attack small fish. They rarely attack animals larger than their body size, but will bite the fins of fish that pass by. They smell blood in water, and the sound of splash attracts them.

Blood in the water, splashing and lots off noise are the activities that trigger aggression from the fish.

The Red-Bellied Piranha fish will show aggressiveness, when they are hungry, during feeding frenzies as they can strip their prey in minutes.

Films on the Piranha fish show the red-bellied feeding on humans, but this is more of a myth than reality, since the humans are not part of the red-bellied piranha diet.

How Do Red-Bellied Piranha Attack?

While the idea that the Amazon is just filled with these Piranhas, roaming around waters just waiting for a human to dip a toe in the water is mainly a myth, it nevertheless still persists.

Local and indigenous people to the Amazon swim happily in the water with Piranhas present, even the Red-Bellied Piranha, one of the most aggressive.

Unless you are threatening the school, they have not eaten and are starving (possibly floodplains and low water season), and are thrashing around while bleeding you remain safe.

Even in the water.

As they are scavenging, if they come across a meat food source that is considerably larger than the individual fish, and it is bleeding, a nip or an initial bite may occur.

There are some stories about people being bitten.

However, the Piranha are likely testing if the food is alive. If there is no movement from the food source, the whole shoal will then take this as a sign to ‘pile in’ and produce the much fabled ‘Piranha frenzy’.

A large ‘food source’ that moves will be treated as a predator. Ironically, they are more afraid of you.

Red-Bellied Piranhas, from a carnivorous point of view, are more likely to attack another, similar sized fish.

A study was conducted in 1972 on just this question. What they concluded was that the ‘first strikes’ against the prey were directed at the eyes and fins.

The study concludes that this strategy is an effective attacking method as it debilitates the victims ability to fight back and makes them defenseless. A fish that cannot see or manoeuvre is a much reduced threat and is excellent for the survival of the Piranha school.

It is Primarily Attracted by Noise, Blood and Splashing

In its natural habitat, the Piranha is attuned to sights and sounds of the natural word. A piece of fruit dropping into the water produces a sound that excites Piranha. As does the thrashing, and possibly bleeding movements of an injured fish.

Scavengers like Piranha, and indeed sharks, use these senses to home in on a food source. It’s a survival instinct for the species.

In relations to humans, a study was performed in 2007 to answer what prompted attacks by Piranha.

In Suriname, where 30 attacks on humans by Piranha had taken place over 12 years in several villages they linked the factors of blood, splashing and noise for the attacks.

Interestingly, there were no deaths in the attacks. Most just received bites on the digits like fingers or toes. In all cases, despite bleeding, and profusely in some cases, the victims were able to walk back to the shore.

It seems if Piranha discover you are not dead, then their interest dies away with it.

The Red-Bellied Piranha is Only a Threat if you Threaten Them

So why do attacks still happen? Why are Piranhas still treated with fear if you are in the water.

One could conclude that those teeth are there for a reason. Why have them if they are not for attacking. The truth is that they are mainly used on fish and dead mammals that float down the river. Remember, the Red-Bellied Piranha is primarily a scavenger.

Although the Red-Bellied piranha is considered, along with the Black Piranha, the most aggressive towards humans, it seems more likely that humans are bitten and attacked because they are a perceived threat.

If you are wandering around the Amazon river, you could get bitten if you are about to step on and disturb a piranha nest. Knowing where they nest, near plants and slow patches of water mitigates the chances of attack.

As a swimmer or as someone playing in the water for fun, then the risk is more on the time of year. Fruit has already dropped, the water level is low and if food is scarce then you might be more likely to be bitten.

It should be known that South American swimming athletes have been known to train in the Amazon without fear of being bitten.

Usually though, it seems Piranha go for extremities, like toes, feet, hands or fingers.

To prove the point;

Red-Bellied Piranha Predators

Although the Red-Bellied Piranha is a predator itself, it is prey to some animals in their natural environment. Large animals in the Amazon prey on the Red-Bellied Piranha and this include the pink dolphin found in the Amazon region.

Some fish-eating birds such as the egrets and storks also feed on the piranha. Alligators also found in the Amazon prey on the red-bellied piranha.

There are also caimans present that see the Piranha as a food source.

A large threat to the fish is actually, us – humans. Humans have been known to enjoy grilled Piranha meat and soup for thousands of years in the Amazon.

Red-Bellied Piranhas for Aquariums

It’s not unknown for the Red-Bellied to be kept in an aquariums at home. They should be fed fresh food, whether frozen or live as they do not feed on rotten meat.

In their natural environment, they feed on live or dead animals; you should note that live feeding to Piranha fish can introduce diseases.

Moreover, the goldfish have a growth-inhibiting hormone which can affect your red-bellied fish. During the juvenile stage, the red-bellied piranha can bite each other thus should be well feed at all times.

The aquarium water should be replaced frequently since the Red-Bellied Piranha is a messy eater and will make the water in the tank dirty. Your aquarium should be dimmed as the fish sometimes indicate signs of shyness, and have plants in the habitat where the fish can hide.

The water needs to be warm as well.

Conclusion

The Red-Bellied Piranha is one of the more common species of Piranha fish It is found in most parts of the Amazon region. The fish lives in the fresh-waters of the rivers in North America such as the Paraguay, Parana, and Essequibo basins.

It is one of the most aggressive Piranha fish and will bite fins of fish that pass-by but it is mostly a scavenger that feeds on seaweeds and plants. Although the fish is a predator, it is prey to some large animals found in the Amazon.

When kept in an aquarium, the fish requires frequent feeding, with regular water change as they are messy feeders.

It is not quite as dangerous as the Hollywood films have made out. While perhaps not being a shy and retiring creature, it nevertheless requires a perceived threat to undertake an attack on a large animal.