Piranhas: Characteristics, types, habitats and more….

Piranhas are freshwater fish that inhabit  South American Rivers and are known for being voracious predators. Keep reading to learn all about them.

These tiny but scaring fish belong to the Serrasalminae subfamily of the the Characidae family, which groups around 30 to 60 species of piranha fish, whose origin dates back to about 100 million years. Some species are more peaceful than others, and can even be raised in aquariums such as the case of the red piranhas

Where does their name come from?

The word piranha is considered by some researchers as coming from the Guaraní language; the official language of the aborigines in Paraguay, Bolivia, part of Argentina and part of Brazil. In this language the term «Pirá» is synonymous with fish while the suffix «Añá» refers to an evil entity that is commonly associated with the devil.

But another interpretation of this name is that equally the word «Pirá» means fish, but with a different suffix called «Rai» which means tooth.

There are also those who affirm that the word comes from the Tupinambá dialect, with «Pirá» equal to fish and «Anhá» a word to refer to the teeth, so it would be translated as «toothed fish».

 In Venezuela the piranhas are also known by the name «Caribe”, referring to a very brave indigenous people who were feared for their anthropophagic customs, especially with the Spanish conquerors.

Main Characteristics Of The Piranhas

The body of most piranhas is sturdy and narrow. They measure between 14 to 26 centimeters in length, although there are species that exceed 40 centimeters.

Their head is prominent and their jaws have a huge strength, with a single row of teeth in each. These teeth have a triangular shape and are quite pointed and the piranhas use them to devour their prey.

In fact, they  have one of the strongest bites among all species of bony fish which is generated by the muscles of the jaw (adductor jaws) and gives them a mechanical advantage that favors the piranhas: the piranhas teethproduction of a force equivalent to 30 times their body weight .

In the case of the black piranha (Serrasalmus rhombeus) this force has been estimated in 320 newtons, which in terms of proportion is twice stronger than the applied by alligators.

As for their color, it is usually silver, red, orange or yellow in the belly area and below the head. They have a dorsal fin located in the back part of the body and an anal fin separated from the caudal fin by the caudal peduncle. We invite you to read our article the anatomy of fish to learn more about this topic

Let´s meet them.

How Do Piranhas Swim?

When the piranha fish swims, it makes a movement that resembles a snake for being undulating. This task is mainly carried out by the strong lateral muscles, helped by the caudal fin. The lower fins are used mainly to help balance functions and in conjunction with the swim bladder give the piranhas the ability to float almost without moving.

Distribution and Habitat

Piranhas are freshwater fish that inhabit almost all rivers in South America except Chile. Their presence is prominent in the Amazon River, in countries such as Paraguay, Peru, Brazil, Ecuador and Bolivia.

They are also very common in the Orinoco River belonging to Venezuela, Colombia and Guayana and in Río de la Plata in Argentina and Uruguay. Moreover, some aquariums in the United States have introduced and raised the piranhas in their waters.

Similarly, there have been some cases of sightings in countries as far away as Bangladesh and China, without knowing exactly how these animals have gotten so far from their native South America.

However, what is known is that these creatures attract certain pet lovers, who when the piranhas become too large for their aquariums they throw them into the lakes, this being one of the possible explanations of why they are found outside of South America.

A 2007 study suggests that modern species separated from a common ancestor around 9 million years ago. In addition, the Atlantic Ocean rose about 5 million years ago, expanding into the flat waters of the Amazon River and other South American rivers.

The environment with high salt content would have been inhospitable for freshwater fish, such as piranhas, but some escaped upstream to higher altitudes. Genetic analysis suggests that piranhas living more than 100 meters in the Amazon have existed for 3 million years.

The Piranhas´ Natural Behavior

Unlike what movies and television have led us to believe, it is not common for piranhas to attack humans. Proof of this is that indigenous natives often bathe in rivers where there is a large concentration of these creatures and in many cases hunt them and then eat them. However, the level of aggressiveness of these fish usually increases during the summer, because the food tends to be scarce and they may be able to attack a person’s foot or hand when mistaken for a prey.

In addition to this, the attacks of the piranha fish occur mainly towards the fishermen in their eagerness to free themselves from the nets.

In incidents with a tragic end, the victim was often already badly wounded or had even died before the piranha’s teeth were pinched.

A heartrending death caused by these Amazonian fish is more typical of horror films than of reality.

The piranha fish lives in banks and / or schools, however they don´t  use any collective strategy to get food. Contrary to what is believed, the training they do to walk in groups is a defense strategy to protect themselves from predators.

The number of piranha fish that are grouped vary according to the level of the water, observing more numerous groups in shallow waters, (in the dry season), when they are more it is more vulnerable to predators.

To create  these schools of fish, a hierarchical system is respected where the largest and oldest specimens travel to the center, being surrounded by the youngest and most inexperienced fish, being exposed to bites and pecks by the animals that use them as food.

here they are

The Origin of Their Reputation.

After two presidential terms, the former president of the United States, Theodore Roosevelt, lost in 1912 the elections to present himself again to the presidential candidacy. After this political defeat, he decided to travel to Brazil to lead a scientific expedition to discover if the river of the Duda flowed in the Amazon River.

During his trip, he saw some piranhas which he described as “the most ferocious fish in the world», describing them in his book «Through the Brazilian Wilderness».

He was very surprised with the skills that piranhas had to eviscerate and devour their preys describing them as follows: «They will tear off the finger of one hand when sliding it carelessly in the water; they mutilate swimmers (in each river in Paraguay there are men who have been mutilated); they will tear and devour any wounded man or beast; because the blood in the water excites them to madness.”

The book of his expedition was a success in sales spreading the bad reputation of which today enjoys the piranha fish.

How  Piranhas Reproduce ?

Piranhas breed during the months of May and June when they are in their natural habitats. They have a slight sexual dimorphism, being in many cases a very complicated task to differentiate the male from the female.

Before spawning occurs, the male builds a nest for the eggs by excavating the river’s substrate. When the home is ready the female proceeds to lay eggs, being able to deposit up to 1,000 eggs on a single occasion, which are then fertilized by the male, who is responsible for their care until the fry are born.

Regarding their longevity, it is worth mentioning that their life expectancy is about 10 years, although it greatly increases when  in captivity (can reach 30 years of existence).

Let´s watch them

Threats and Predators

Although it seems hard to believe, piranhas also have their predators, among which are crocodiles, Amazonian river dolphins and herons.

However, as in the case of many fish and animals, their main threat is the human being who usually catches this animal for various purposes.

First of all, the piranhas  are used  as food by both native and by many restaurants in the area that offer this fish as a local dish or some preparations that include its meat. A second use relies in their sale and commercialization as aquarium pets, but to own a fish like this one must know perfectly the requirements and precautions that must be taken for its care.

enjoy your meal

Fishes Immune to the Piranhas Attacks.

Although it seems impossible to believe, there are fish that are able to resist the piranha´s bites , which allows them to swim unharmed in the  Amazon River waters

Marc Meyers is a mechanical engineer member of the University of California, who was amazed by how the piranha fish avoided the succulent flesh of the Arapaima or Paiche fish, carried out a research in this topic. In his laboratory, Meyers and his team reproduced several scales of the Arapaima fish, and the piranha fish’s teeth, to apply the pressure equivalent to their bite with a machine. Surprisingly when starting the test the teeth broke.

The secret of the Arapaima fish to avoid predators, relies on their scales composed of two layers, an interior made of collagen and superimposed with another outer one also made of collagen, pre reinforced with calcium, forming a strong armor. The pattern of hard materials on soft gives resistance, but without sacrificing the required flexibility to move.

What do Piranhas Eat?

Piranhas are omnivorous fish, that is, they can eat any type of food. Generally they eat insects, fish, crustaceans, invertebrates, some small terrestrial animals that fall into the water, although they can also eat seeds, fruits, aquatic plants and in times of crisis, even carrion.

Piranhas attack the eyes or tails of other fish to immobilize them and then eat them without consideration. Their sharp, pointed and thin teeth exert a rapid puncture followed by an incisive cut.

Main Types of Piranhas

There are many varieties of piranha fish, among which the most common are the red piranha, the black piranha, the mouth of fire and the piraya. Their main differences lie in the color of their skin. We invite you to know them a little more thoroughly.

Red Piranha (Pygocentrus nattereri).

This species is also called common piranha because it is the most found in the South American rivers. The adult male can measure up to 35 centimeters in length and 3 kilograms in weight.

 Their dorsal fin is located further back than in other types of fish, while the anal is separated from the caudal only by a caudal peduncle; unusual condition in teleost fish

Their head is prominent and their jaw is usually more outward than the upper jaw, so that the tip of the teeth can be seen in many specimens. This data is fundamental to differentiate them from the pacu, who are similar but are not piranhas.

When they are young, their skin is very silvery with small black spots, but as they grow, the black spots will begin to disappear to give way to an intense red coloration in the abdominal area. In turn, the silvery will become darker, taking a slightly greenish or bluish tone depending on each specimen.

The iris of their eyes is an intense orange color, which gives them a chilling appearance. The red or common piranhas are found especially in countries like Paraguay, Paraná, Esquivo and Uruguay.

Black Piranhas  (Serrasalmus rhombeus.)

Their body has the typical rhomboid shape being more elongated in juvenile specimens while in adults it is deeper and the head is more robust and flat with a short snout.

Their head is silver-colored highlighting their eyes of intense red, giving it a terrifying appearance.

As for their eyes, they´re crossed by a vertical black band, at the same time that the body has a silvery, leaden color with a somewhat diffuse opercular stain.

The abdominal area presents few or no spots, having a yellow or orange color according to the age of the piranha. The anal fin is yellow, and the tail fin has a black band at the base and a terminal strip that is more evident in young adults.

When they adulthood their body color acquires a very dark homogeneous lead tone. White and clear waters comprise their common habitat, so it is common to see them in pipes and streams of plains, forests and flooded savannas belonging to Venezuela.

Let´s watch them


Care of Piranhas in Aquariums

There are many types of piranhas, the most aggressive being the red and the black, but at the same time the most sought after to breed in aquariums. The suitable the water temperature for them, ranges between 20 and 28º C  with an  alkaline value of 5.5. On the other hand, the hardness must be maintained between 10 and 20.

In what you must be very careful is that water filtration is effective and fast, since piranhas produce a large amount of waste that also have high protein content.

The main limitation that many people have when raising a piranha fish, is that they don´t know the dimensions that they will reach when they get older, since they usually sell them when they are still young.

This means that by not having enough space for their development the animals die. When you raise a piranha fish, remember not to put your hand in the fish tank, because you could be strongly bitten. This precaution should be considered to the maximum, if for some reason you have a wound in your hand that has blood and attracts the attention of the piranha fish.

Feeding Piranhas in Captivity

The amount of food required  to keep the piranhas in good health, depends on their age. If they are fed more than necessary they become overweight , which is  a very frequent fact that should be avoided.

They can be fed with small pieces of raw meat, small fish or pieces of fish; in addition to alive or frozen worms. This last type of food (frozen) is even more recommended for them since it destroys most of the parasites. Krill and other small frozen fish are also recommended for this purpose.

You have to be especially careful with the remains of food and waste in the aquarium, so as not to compromise the water´s quality  when they decompose.  While it´s  true that  piranha fish is able to consume carrion or meat that is a bit decomposed, they only do so  in case of lack of food and is not recommended.

Let´s watch and learn

How large should the Aquarium Be?

The aquarium of our piranha must be large enough to house the fish when it reaches adulthood. A 75 L tank may be suitable for half a dozen 5 cm piranhas, but the minimum size needed for two or three adult red-bellied piranhas will be approximately 200 liters.

Compatibility with Other Fish.

The piranha fish is a predatory animal, that is, she can eat any fish that you introduce with her in the aquarium. For this reason it is better to keep them in tanks of unique species but this doesn´t mean that they should be completely alone; you can keep up to 5 specimens of these fish in an aquarium with a capacity of 100 liters. A lot of attention must be paid not to place many individuals together, since they can fight with each other for space, especially when food scarce.

Reproduction in Aquariums.

There´s not a big deal for you piranha to reproduce in aquariums but you must have more than one tank, because when the fry are born, you must separate them from the parents to avoid being eaten, as happens with more common fish in aquariums like guppy and molly. In addition, the offspring must be classified by size.

You should always feed the little ones with live food, and never neglect a meal or skip it, because in this way you avoid cannibalism among the brothers, mainly by the larger specimens that can be eaten by the little ones.

When it is young, the piranha fish is golden colored on the underside of its body with small spots or spots on the sides. When they become adults their color changes, turning a dull gray with tiny pints that look like silver sparkles.

Let´s have a final look of them.


Deja un comentario