Giant predatory fish arapaima. Arapaima gigas: habitats and habits of the giant pirarucu fish
Arapaima (lat. Arapaima gigas) is a freshwater fish of the suborder Osteoglossidae of the order Osteoglossiformes.
One of the largest freshwater fish, individual specimens reach 3 meters in length and weigh 200 kilograms.
These giants live in freshwater bodies South America, in particular in the eastern and western parts of the Amazon River basin (in the Rio Moro, Rio Pastaza and Lake Rimachi rivers). Reservoirs with rugged banks and a large number of floating plants - here perfect place for its habitation and existence.
One of the most valuable commercial species South America, often caught using nets and harpoons, so specimens longer than 2 meters are now rare.
Previously, arapaima was caught in large quantities and did not think about its population.
Now, when the stocks of these fish have noticeably decreased, in some countries of South America, for example in eastern Peru, there are areas of rivers and lakes that are strictly protected and fishing in these places is allowed only with a license from the ministry Agriculture, and in some areas of distribution fishing is prohibited.
The powerful body of the fish is covered with large scales, which shimmer in various shades of red. This is especially noticeable in its tail part. For this, local residents gave the fish another name - piraruku, which translates as “red fish”. The fish themselves have different colors - from “metallic green” to bluish-black.
The fish does not have significant competition for life resources due to its unique adaptation mechanism - the arapaima can breathe air due to the lung-like tissue that lines the pharynx and swim bladder.
The swim bladder of the arapaima is lined with lung tissue.
This adaptation developed due to the low oxygen content in the waters of the Amazon. Thus, arapaima can survive drought by swallowing air and burrowing into the mud and sand of swamps.
The breathing style of this fish cannot be confused with anyone else. When they rise to the surface for a sip fresh air, then small whirlpools begin to form on the water surface, and then the fish itself appears in this place with a huge open mouth. All this action lasts literally a couple of seconds. She releases the “old” air and takes a new sip, the mouth closes sharply and the fish goes into the depths. Adults breathe like this every 10-15 minutes, young ones - a little more often.
Arapaima skull and jaws
Arapaima feeds on fish and other small animals, including birds. For juveniles, the main dish is freshwater shrimp.
The breeding season of arapaima occurs in November. But they begin to create pairs already in August-September. These giants are very caring parents, especially the males. The male digs a shallow hole with a diameter of about 50 centimeters near the shore. The female lays eggs in it.
Throughout the entire period of development and maturation of the eggs, the male remains close to the clutch. He guards the eggs and swims next to the “nest,” while the females drive away the fish swimming nearby.
A week later the fry are born. The young stay in a dense flock near the male’s head, and they even rise together to breathe. These fish have glands on their heads that secrete a secretion; the smell of this secretion attracts the fry, forcing them to stay close to their parents. But after 2.5-3 months, when the young animals grow a little, these flocks break up. The bond between parents and children weakens.
Scientific classification
Kingdom: Animals
Type: Chordates
Class: Ray-finned fish
Squad: Bony-tongued
Family: Bony tongue
Genus: Arapaima
View: Arapaima gigas
It is difficult to call the giant arapaima (lat. Arapaima gigas) a fish for a home aquarium, since it is very large, but it is also impossible not to talk about it. In nature, it reaches an average body length of 200 cm, but larger specimens, more than 3 meters in length, have also been documented. And in the aquarium it is smaller, usually about 60 cm. This monstrous fish is also known as pirarucu or paiche. This is a formidable predator that eats mainly fish, fast and swift. She can also, like the arowana, which is somewhat similar to her, can jump out of the water and grab birds and animals sitting on the branches of trees.
Of course, due to its enormous size, arapaima is not suitable for home aquariums, but it can often be seen in zoos and animal exhibitions, where it lives in large pools stylized as its homeland - the Amazon. Moreover, it is even banned in some countries, due to the danger that, if released into nature, it will destroy local species fish Of course, this does not threaten us, because climatic conditions.
IN this moment, detecting a sexually mature individual in nature is not an easy task for biologists. Arapaima has never been a very common species, and is now becoming even less common. Most often it can be found in wetlands, with low content oxygen in water. To survive in such conditions, arapaima developed a special Breathe-helping machine, allowing her to breathe atmospheric oxygen. And to survive, she needs to rise to the surface of the water for oxygen every 20 minutes.
In addition, pirarucu has been the main source of food for the tribes inhabiting the Amazon for many centuries. It was precisely the fact that she rose to the surface for air that killed her; people tracked down this moment, and then killed her with the help of hooks or caught her in a net. Such extermination significantly reduced the population and put it at risk of destruction.
Amazonian arapaima (lat.Arapaima gigas) was first described in 1822. It lives along the entire length of the Amazon and in its tributaries. Its habitat depends on the season. During the dry season, arapaima migrates to lakes and rivers, and during the rainy season, to flooded forests. Often lives in swampy areas, where it has adapted to breathe atmospheric oxygen, swallowing it from the surface.
In nature, sexually mature arapaima feed mainly on fish and birds, but juveniles are much more insatiable and eat almost everything - fish, insects, larvae, invertebrates.
Description
The arapaima has a long and elongated body with two small pectoral fins. The body color is greenish with various tints, and reddish scales on the belly. It has extremely hard scales that are more like a shell and are very difficult to penetrate. This is one of the largest freshwater fish; in an aquarium it grows about 60 cm and lives for about 20 years. And in nature average length 200 cm, although there are more large individuals. There is evidence of an arapaima 450 cm long, but it dates back to the beginning of the last century and is not documented. Maximum confirmed weight is 200 kg. The young remain with their parents for the first three months of life and reach sexual maturity only at 5 years.
Difficulty in content
Despite the fact that arapaima is very undemanding, but due to its size and aggressiveness, keeping it in home aquarium doesn't seem real. She needs about 4000 liters of water to feel normal. However, it is very often found in zoos and various exhibitions.
Feeding
A predator that feeds mainly on fish, but also eats birds, invertebrates, and rodents. Characteristically, they jump out of the water and grab animals sitting on tree branches. In captivity, they feed on all types of live food - fish, rodents and various artificial foods.
Feeding in the zoo:
Sex differences
It is difficult to determine whether during spawning the male becomes brighter than the female.
Breeding
The female reaches sexual maturity at the age of 5 years and with a body length of 170 cm. In nature, arapaima spawn during the dry season, from February to April they build a nest, and with the beginning of the rainy season, the eggs hatch and the fry ends up in ideal conditions for growth. They usually dig a nest in the sandy bottom, where the female lays her eggs. The parents guard the nest all the time, and the fry remain under their protection. at least within 3 months after birth.
Jul 2, 2014 admin
Considered one of the largest freshwater fish today, the arapaima has many names. Pirarucu is one of them, as this fish is called by the natives of Peru. It translates as “red fish” and is due to the red hue of the meat and rich red spots on the scales. Close relatives of this giant fish are considered arowanas. All these freshwater animals belong to the Aravanidae group.
![](https://i2.wp.com/rybki.guru/wp-content/uploads/2018/07/arapajma-gigas.jpg)
General information
Unfortunately, the lifestyle of these ancient freshwater animals has been practically not studied. The main sources of information are various narratives of tourists, which are often unreliable. Locals, which long years engaged in arapai fishing, no scientific research were not produced. The Indians saw the “red fish” only as a source of food.
The Latin name "Arapaima gigas" was formed by combining several words from different languages. The people of Peru called the fish arapaima or arapaima. "Gigas" means "giant" in Latin. Other names, pirarucu and paiche, may have come from one of the local dialects.
Locals call this fish pirarucu and paiche.
Habitat
Arapaima gigas are found in Guyana, Peru and Brazil - in rivers that connect to the Amazon. In the Amazon itself, arapaima fish can be found quite rarely. She prefers rugged coastlines of bodies of water, which are overgrown with coastal algae, when large floating meadows are formed, in which the fish are almost invisible.
It can also be found in swamps and lakes, and during the monsoon season - also in tropical forests which were flooded. The water in its habitat is quite warm (26−30 degrees), the pH level is 5.2−5.7 (“slightly acidic” reservoirs), with a water hardness of 12. Most of the time the fish sticks to the bottom.
External description
Pirarucu fish has a rather exotic appearance. The body is compressed at the sides and has a long shape:
- The scales have a relief shape, are hard and quite large sizes. The diameter of the scales of an average individual is more than five centimeters. The ends of all scales have a rich red border.
- The mouth is quite large and has an upper position.
- The head is significantly elongated and flattened closer to the top, so it looks small against the background of the gigantic body. On top there are keratinized plates.
The strength of the scales of this fish is unique. The elasticity coefficient (a physiological indicator of the ability of a body or substance to deform under the influence of mechanical force) is tens of times higher than that of the bone skeleton.
![](https://i2.wp.com/rybki.guru/wp-content/uploads/2018/07/arapajma-cheshuya.jpg)
The scales have a multi-layered structure, due to this the arapaima can survive when it is in the vicinity of piranhas in small reservoirs that are separated from the river during drought.
An adult arapaima has different shades:
- the head in front has a brown-olive color, casting a green-blue tint;
- near the pelvic fins a transition to pink begins to occur and closer to the tail part the body becomes dark red.
The location of the fins is quite peculiar. Unpaired fins are displaced quite close to caudal fin and very large, while looking almost symmetrical. The paired ventral fins are also strongly displaced towards the caudal region.
The crowded location of the fins is quite conditioned. The wide tail blade and all three fins simultaneously create an “oar”, allowing the fish to attack its prey and giving acceleration.
Body size
There is an opinion that the most large individuals reached 4.6 meters. But scientific evidence it doesn't exist. The record length is a specimen measuring 2.49 meters, which was caught in 1979 in Brazilian waters.
In the work "Fishes of Guiana", which was written by Shom Burkum after traveling to this country in 1837, it is written that greatest length piraruku equals 15 feet (437 cm). However, this size is taken from Aboriginal stories. Therefore, there are certain doubts about the reliability of this information.
![](https://i1.wp.com/rybki.guru/wp-content/uploads/2018/07/arapajma-vyrastaet-do-dvuh-metrov.jpg)
Respiratory system
Piraruku - no the only fish which can breathe atmospheric oxygen. Its close relatives also have this ability - arowanas, for example, the platinum arowana.
Living in bodies of water with a small amount of oxygen occurs due to the special structure of the swim bladder, which plays the role of a lung:
- The swim bladder is quite large.
- The tissues of the bladder have cellular walls, where there is a huge network of blood capillaries.
The gill respiration of the pirarucu can provide only 25% of the fish's oxygen needs; the remaining 75% of the arapaima's oxygen is obtained from atmospheric air. To do this, an adult floats up to the surface of the reservoir every 20 minutes. Young animals need to surface for oxygen more often.
Sticking its mouth out of the water and opening it wide, the arapaima makes a clicking sound, thereby releasing air from the bubble, drawing in a new portion of oxygen.
Piraruku vulnerability
"Pulmonary" respiratory system This fish is so specific that it made it quite vulnerable. The sound that is made when the mouth opens is a signal for fishermen.
If arapaima swims to the surface, then the water surface begins to resemble a whirlpool. The fishermen immediately notice him and throw a sharp harpoon into the center of the whirlpool. It's not always possible to hit the fish.
Swimming out from the center of the whirlpool with a wide open mouth, the piraruku releases “recycled” oxygen with a sharp sound, immediately inhales and immediately closes its mouth, sinking to the bottom. This lasts no more than 2-3 seconds.
![](https://i1.wp.com/rybki.guru/wp-content/uploads/2018/07/arapajma-delaet-vdoh-na-poverhnosti-vody.jpg)
Anglers prefer to catch arapaima in small (no more than 120 meters in size) lakes, in which it is quite easy to notice whirlpools. And in certain moment fishermen may be lucky - they will fall into the body of a fish that has risen to breathe air.
Security measures
For a long time, the meat of this fish has been the basis of the diet of the inhabitants of the Amazon, just like arowanya - of the population of Asia. But as soon as nets began to be used, the piraruku simply disappeared in most rivers. If only an adult individual could be caught with a harpoon, then fry were also caught with a net, so the population began to decline significantly. Fish larger than two meters have become caught quite rarely.
![](https://i1.wp.com/rybki.guru/wp-content/uploads/2018/07/ohota-na-arapajmu.jpg)
The situation became an incentive to create special events to limit production, preserve stocks and combat poaching. For example, in one region of Peru there are reservoirs and areas of certain lakes in which fishing for pirarucu is permitted only with a special license issued by the Ministry of Agriculture.
Piraruku, just like the Asian Arowana, is on the CITES list. Arapaima is in “Appendix No. 2” - like an endangered fish complete disappearance and with the need for clear regulation of trade in its meat. It is prohibited to sell fish smaller than 1.5 meters in size.
Another threat to arapaima is deforestation:
- In flooded forests during the rainy season, arapaima breed and raise young.
- Vegetation is a refuge for young animals, which are susceptible to attack by predatory animals.
Reproduction and breeding of arapaima today is carried out in artificial lakes and pond farms in various parts of the Earth. So, this fish is grown in Thailand. It was brought to this country for cultivation as an object for sport fishing. Fishing on the lakes is a fairly popular activity among vacationers.
In Peru, a number of lakes are protected - piraruca are grown in them to study behavioral characteristics. In Brazil, arapaima were also introduced into special reservoirs for further research.
Reproduction methods
Reproduction of arapaima and especially caring for offspring is a rather touching process. After 5 years of life, the arapaima is sexually mature. Breeding begins in December and pairs form around November. There is an unproven hypothesis that sexually mature individuals can spawn twice a year.
These giant fish are quite caring parents. Together they protect the nest with the eggs in it.
Spawning begins to occur near the shore- in the shallows. The nests are prepared exclusively by the male. It is believed that it digs a hole for eggs in clay soil with its mouth. The size of the hole is approximately 50 cm, and it is shallow. The female lays eggs in this nest. There is no information yet on the number and diameter of eggs.
After the eggs are fertilized in the spawning area, the male guards them. He is regularly located near the hole. The female also does not leave the area adjacent to the nest and remains at a distance of 20 meters from it, driving away fish that approach at a very close distance.
Appearance of young animals
The male arapaima continues to guard and protect the offspring even after the fry appear. For about another 7-10 days, the hatched offspring live in the nest under the supervision of their parents. When arapaima babies swim out of the spawning area, they are always near the male’s head. Local residents believe that this is how the young animals receive “parent’s milk.”
Of course, the male arapaima does not have any “milk”. Just on your head adult There are special glands that secrete mucus. The whole secret that explains the crowding of babies near the male’s head lies in a special substance that is found in the mucus. The produced substance attracts the fry all the time and forces them to stay in the flock. At the same time as the male, the babies float to the surface of the water for the first time to inhale oxygen.
This amazing and unique connection with the male lasts up to 3 months. The kids grow up, and the connection with the parent is lost. The flock breaks up, and all individuals begin life separately.
![](https://i1.wp.com/rybki.guru/wp-content/uploads/2018/07/molodnjak-arapajmy.jpg)
Nutritional Features
Arapaima is a predator. Considering the size of this fish, you can easily understand that almost any inhabitant of the Amazon can be its prey. First of all, arapaima hunt invertebrates rich in fish proteins. Also, pirarucu does not disdain carrion and can eat what piranhas could not eat.
Regardless of huge size, arapaima can develop high speed, catching up with its prey. Piraruku can jump out to catch unwary prey. When jumping, a fish is able to grab a bird located on a tree hanging over a pond.
![](https://i2.wp.com/rybki.guru/wp-content/uploads/2018/07/arapajma-bolshe-provodit-vremeni-vozle-dna.jpg)
The whitebait typically feeds on shellfish. As they grow older, fish and small animals begin to be added to the menu. This type of fish spends most of its time near the bottom, so bottom food makes up the main portion of its diet. There is no complete picture of the diet of these giants due to insufficient knowledge of pirarucu.
Arapaima is a real living relic, a fish that is the same age as dinosaurs. This amazing creature, living in the rivers and lakes of South America, is considered one of the largest freshwater fish in the world: only some beluga individuals can exceed the arapaima in size.
Description of arapaima
Arapaima is a relict freshwater fish that lives in the tropics. It belongs to the Aravanaceae family, which, in turn, belongs to the Aravanidae order. Arapaima gigas - that's exactly what it sounds like scientific name. And this living fossil has a number of unique features.
Appearance
Arapaima is one of the largest freshwater fish: it usually grows up to two meters in length, but some of the representatives of this species can reach a length of three meters. And, if you believe eyewitness accounts, there are also arapaima up to 4.6 meters in length. The weight of the largest specimen caught was 200 kg. The body of this fish is elongated, slightly flattened laterally and strongly tapering towards a relatively small elongated head.
The skull has a slightly flattened shape on top, the eyes are shifted to the bottom of the muzzle, not too big mouth located relatively high. The tail is strong and powerful, thanks to it the fish can make powerful, lightning-fast throws and it also helps it jump out of the water in pursuit of prey. The scales covering the body are multi-layered in structure, very large and embossed. The head of the fish is covered with bony plates.
This is interesting! Thanks to its unique, incredibly strong scales, ten times stronger than bone, arapaima can live in the same reservoirs with piranhas, which do not even try to attack it, without any harm to itself.
The pectoral fins of this fish are located quite low: almost near the belly. Dorsal and anal fins relatively long and as if shifted towards the tail itself. Thanks to this arrangement, a kind of oar is formed, which gives the fish acceleration when it rushes towards prey.
The front part of the body of this living relic is colored olive-brown with a bluish tint. Near the unpaired fins, the olive color smoothly flows into reddish, and at the level of the tail it becomes dark red. The tail is shaded by a wide darkish border. Gill covers can also be colored reddish. Sexual dimorphism in these fish is quite pronounced: the male has a slimmer body and is brighter in color. And only young individuals, regardless of their gender, have a similar, not too bright color.
Behavior, lifestyle
Arapaima tries to adhere to a benthic lifestyle, but it can also hunt closer to the surface of the reservoir. This big fish It is constantly in search of food, so it is rarely possible to see it motionless, except perhaps at the moment of tracking prey or taking a short rest. Arapaima, thanks to its powerful tail, can jump out of the water to its entire length, that is, 2-3, and possibly 4 meters. She often does this when pursuing her prey, who is trying to fly away from her or escape along low-growing tree branches.
This is interesting! The surface of the pharynx and swim bladder this one amazing creation permeated with a dense network blood vessels, and in its structure it resembles cells, which makes it similar in structure to lung tissue.
Thus, the pharynx and swim bladder of this fish also serve as an additional respiratory organ. Thanks to them, arapaima can breathe atmospheric air, which helps it survive drought.
When bodies of water become shallow, she buries herself in wet silt or sand, but at the same time rises to the surface every few minutes to take a breath of air, and she does it so noisily that the sounds of her loud breaths are carried far throughout the entire area. Call arapaima decorative aquarium fish it is impossible, however, it is often kept in captivity, where, although it does not grow to a particularly large sizes, but it can easily reach a length of 50-150 cm.
This fish is often kept in zoos and aquariums. Keeping her in captivity is not very easy, if only because you need huge aquarium and constant maintenance comfortable temperature. After all, a decrease in water temperature even by 2-3 degrees can lead to very unpleasant consequences for such a heat-loving fish. Nevertheless, arapaima is even kept by some amateur aquarists, who, of course, can afford to create suitable living conditions for it.
How long does arapaima live?
About how long such giants live in natural conditions, there is no reliable data. Considering that in aquariums such fish, depending on the conditions of existence and the quality of care for them, live for 10-20 years, we can assume that in natural environment habitat, they live for at least 8-10 years, unless, of course, they are first caught by fishermen in a net or harpoon.
Range, habitats
This living fossil lives in the Amazon, in countries such as Peru, Ecuador, Colombia, Venezuela, French Guiana, Suriname, Guyana and Brazil. This species was also artificially introduced into the water bodies of Thailand and Malaysia.
Under natural conditions, fish prefer to settle in river backwaters and lakes overgrown with aquatic vegetation, but they are also found in other floodplain reservoirs with warm water, the temperature of which ranges from +25 to +29 degrees.
This is interesting! During the rainy season, arapaima tends to move to flooded floodplain forests, and with the onset of the dry season, they return back to rivers and lakes.
If, with the onset of drought, it is not possible to return to its native body of water, the arapaima survives this time in small lakes that remain in the middle of the forest after the water recedes. Thus, back to the river or lake if she is lucky enough to survive dry period, the fish return only after the next rainy season, when the water begins to recede again.
Arapaima diet
Arapaima - dexterous and dangerous predator, the majority of whose diet consists of small and medium-sized fish. But she won’t miss the chance to hunt small mammals and birds sitting on tree branches or going down to a river or lake to drink.
Young individuals of this species are generally extremely indiscriminate in food and eat everything: small fish, larvae and adult insects, small snakes, small birds or animals, and even carrion.
This is interesting! The favorite “dish” of the arapaima is its distant relative, the arawana, which also belongs to the order arawana-like.
In captivity, these fish are mainly fed protein foods: they are fed cut sea or freshwater fish, poultry, beef offal, as well as mollusks and amphibians. Considering that in its natural habitat the arapaima spends a lot of time chasing prey, they are released into the aquarium where it lives small fish. Adults feed in this way once a day, but juveniles should feed three times, no less. If feeding is delayed, then grown-up arapaima may begin to hunt fish living in the same aquarium.
Reproduction and offspring
Females can breed only after they reach the age of 5 years and a size of at least one and a half meters. In nature, arapaima spawning occurs at the end of winter or early spring: approximately in February-March. At the same time, the female prepares the nest for laying eggs in advance, even before spawning. For these purposes, she chooses a shallow and warm reservoir with a sandy bottom, where there is no current at all or it is barely noticeable. There, at the bottom, she digs a hole from 50 to 80 cm wide and 15 to 20 cm deep, where later, returning with the male, she lays eggs, which are large in size.
After about two days, the eggs burst and the fry emerge from them. All this time, from the laying of eggs by the female until the moment when the juveniles become independent, the male is close to his offspring: protects, looks after, cares for and even feeds them. But the female also does not go far: she guards the nest, moving away from it no more than 10-15 meters.
This is interesting! At first, the fry are constantly near the male: they even feed on the white substance secreted by the glands located near his eyes. Due to its specific smell, this same substance also serves as a kind of beacon for small arapaima, telling the fry where they should swim so as not to lose sight of their father.
At first, the juveniles grow quickly and gain weight well: on average, in a month they grow by 5 cm and add 100 grams. The fry begin to lead a predatory lifestyle within a week after their birth, and at the same time they become independent. At first, when they start hunting, they feed on plankton and small invertebrates and only later switch to small fish and other “adult” prey.
However, adult fish continue to three months look after your offspring. Perhaps this care, so unusual for other fish, is explained by the fact that arapaim fry do not know how to breathe atmospheric air until a certain age, and their parents later teach them this.
Natural enemies
In its natural habitat, the arapaima has practically no enemies, since even piranhas are unable to bite through its surprisingly strong scales. There are unconfirmed reports that these fish are sometimes hunted, but this, according to eyewitnesses, happens extremely rarely.
This fish, which is considered one of the largest freshwater fish modernity, there are several names. Pirarucu fish is one of them, which is what the Indians of Brazil call it. This name means “red fish” and is associated with the reddish color of its meat and bright red spots on its scales and fins.
The closest relatives of this giant are. All of them belong to the order Aravan-like or bone-tongue-like. The Latin name for the fish pirarucu (Arapaima gigas) is formed by combining two words from different languages . The Indians of Guiana call it arapaima fish or arapaima. Latin word " gigas"
means gigantic. There is another name for this fish - paiche, probably also in one of the Latin American dialects.
Unique Features of Arapaima or Pirarucu
Each inhabitant of our planet is unique and inimitable, and when we talk about animals such as the giant arapaima fish, the surprise is simply off the charts. Unfortunately, the lifestyle of these ancient fish has been studied very little. The main sources of information are stories from travelers, which are often unreliable. The local Indian population, who had been fishing for arapaima for many years, did not conduct any scientific observations. They saw it only as a source of food, because its meat is tasty.
Where does it live? The giant arapaima fish lives in Brazil, Peru and Guyana in rivers flowing into the Amazon. Directly in the Amazon it is not found very often. The fish prefers rugged shores, overgrown with coastal floating plants, the interweaving of which forms peculiar floating meadows, among which this huge fish is invisible. It is also usually found in lakes and swamps, and in rainy season it can also be found in floodplain forests that have been flooded. The water in the arapaima habitat is very warm (25 – 29 degrees), the pH is 6 – 6.5 (water is “slightly acidic”), and the hardness is 10. Most
she spends time at the bottom.
Size and appearance
- Arapaima or paiche fish has such an exotic appearance that you want to carefully examine almost every part of its body, which has an elongated shape and is laterally compressed:
- The head is noticeably elongated and, as it were, flattened on top, so that it looks small against the background of the huge body. The top of the head is protected by bone plates.
- The mouth is upper and very wide.
Several photos of piraruku fish below demonstrate the above-described features of its appearance.
The phenomenality of arapaima scales
The strength of arapaima scales is so phenomenal that it is difficult to imagine. The modulus of elasticity (a physical measure of the ability of a body or substance to undergo deformation under the influence of force) was 10 times higher than that of bone.
The scales have a multilayer structure, thanks to which arapaima is able to survive safely while in the company of piranha natterera in small reservoirs separated from the river during the dry period.
Color and fins
Adult arapaima in different parts the body has different shades of color:
- the head and the front part of the body are brownish-olive, tinged with a greenish-gray color;
- starting from the pelvic fins, the color of the body gradually changes to reddish and at the tail it becomes dark red.
The arrangement of the fins is very peculiar and characteristic of arapaima:
- The unpaired ones (dorsal and anal) are quite long and are located very close to the caudal fin and look almost symmetrical.
- The ventral paired fins are also noticeably shifted towards the tail.
This crowded arrangement of unpaired fins has a justification. All three of these fins and the wide caudal peduncle together form an “oar”, which effectively helps the fish attack its prey - giving it acceleration.
Length
It is believed that the largest specimens of arapaima reached a length of 450 centimeters. However, there is no documented data about this. The record size is considered to be a specimen 248 centimeters long, obtained in 1978 in Brazil.
In the book “Fishes of British Guiana,” which Shom-burk wrote after his trip to Guiana, which took place in 1836, it is noted maximum length arapaima fish, equal to 14 feet (427 centimeters). But this figure is not the result of his personal measurements, but is taken from the stories of the local population. Therefore, there may be doubts about its reliability.
Breathing atmospheric air
Arapaima is not the only fish that can breathe oxygen from the air. Her closest relatives, the arowanas, have the same ability, for example, the unique one.
Living in oxygen-deficient water bodies is possible thanks to special structure swim bladder of a fish, performing the functions of a lung:
- The swim bladder is very large.
- The walls of the bladder are formed by cellular tissue, in which there is a dense network of blood vessels.
The gill respiration of the arapaima provides only a fifth of its oxygen needs, the remaining 80 percent required oxygen it receives from atmospheric air. For this purpose, adult fish are removed every 15 minutes. floats up to the surface of the water. Young individuals need to rise for air more often.
Sticking its head out of the water and opening its mouth wide, the fish makes a peculiar clicking sound, releasing air from its swim bladder and drawing in the next portion.
Arapaima vulnerability
The “pulmonary” breathing of the arapaima is so specific that it makes it incredibly vulnerable. The sound made when opening the mouth is a kind of signal for fishermen.
When the paiche fish rises to the surface, the water surface turns into a nice whirlpool. The fishermen immediately notice him and throw a heavy harpoon into the middle of the whirlpool. It is not always possible to hit the target.
Appearing from the middle of the whirlpool with its mouth wide open, the arapaima noisily releases “exhausted” air, immediately takes a sip, immediately closes its mouth and abruptly goes into the depths. This lasts no more than a few seconds.
Fishermen prefer to hunt arapaima in small (up to 160 meters long) bodies of water, where it is very easy to notice whirlpools. And at some point luck may “smile” on them - there will be perfect hit a harpoon into the body of an arapaima that had risen to breathe.
Threats and security
For a very long time, pirarucu meat was the basis of the diet among the peoples of the Amazon, just as in South-East Asia. But as soon as nets began to be used to catch it, arapaima disappeared in many rivers. If you only got it with a harpoon big fish, young individuals began to be caught with nets, so the population began to decline sharply. Fish two or more meters long began to be caught very rarely.
The situation described above was an incentive to develop measures to limit fishing, combat poachers, and preserve stocks. For example, in one of the eastern provinces of Peru, lakes and areas of some rivers have been identified where the extraction of arapaima is permitted with a license issued by the Ministry of Agriculture.
Like the pirarucu (aka arapaima), it is listed on the CITES list. It is listed in Appendix 2 as a potentially endangered species requiring strict regulation of trade in its specimens.
Specimens less than one and a half meters long are prohibited for sale.
The second threat to arapaima is biological species, is deforestation. Why:
- In flooded forests at the onset of the wet season, the pirarucu reproduces and raises offspring.
- Vegetation is a refuge for juveniles, which are subject to strong pressure from predators.
Reproduction
Breeding and reproduction of arapaima in pond farms and artificial reservoirs are engaged in different places Lands:
- It is bred in Thailand, where it was brought for the purpose of cultivation as an object for sport fishing. Fishing on the lakes is a very popular activity among tourists.
- In Peru, some reservoirs are protected to organize the breeding of arapaima in them in order to study its biology.
- In Brazil, arapaima were introduced into special ponds with the prospect of studying it.
Reproduction
Breeding pirarucu and especially caring for babies is a very touching process that demonstrates high degree the care of these fish. At the age of 5 years, the piraruku becomes sexually mature. Reproduction occurs in November, and pairs are created in advance - in August and September. There is an unproven suggestion that adults can reproduce twice a year.
These huge fish are very caring parents. Together they guard the nest with developing eggs.
Spawning occurs near the shore at shallow depths (about one and a half meters). The male prepares the nest. It is assumed that it digs a spawning hole in clayey soil with its mouth. The diameter of the hole is about half a meter, and it is shallow. The female spawns eggs into such a nest. There is no data on the size and number of eggs.
After fertilization of the egg laying, the male begins to guard it. He is constantly near the nest. The female also does not leave the territory adjacent to the nest, and swims at a distance of 10-15 meters from it and drives away fish that come too close.
After the fry appear, dad takes care of them
The pirarucu father continues to protect and care for his offspring even after the fry hatch from the eggs. For another week, the hatched babies remain in the nest under the careful supervision of the male: they either circle above the nest or are on the side.
When the pirarucu fry leave the nest, they remain constantly near their father's head. Local population assumed that in this way the juveniles receive “parental milk.”
But, of course, papa piraruku cannot have any “milk.” On the head of an adult male there are special glands that secrete mucus. You can try to see the holes through which this mucus is secreted in the photo of the pirarucu fish: there are small protrusions on the head that resemble tongues. If you take a magnifying glass, you can even see them in this photograph.
At the ends of these protrusions, tiny holes are visible, through which mucus is released. The whole secret that explains the crowding of fry at the male's head lies in a special substance contained in the mucus. This substance constantly attracts young fish and makes them swim in a school. Together with the male, the fry rise to the surface for the first time and inhale air.
This unique and amazing bond with the father can last up to three months of age. During this time, the young grow up, and the connection between the little arapaima and their parents weakens. The flock breaks up, and each individual begins an independent life.
What does arapaima eat?
Arapaima – predatory fish. If you look at its skeleton, you will notice a strong skull and a powerful rear part of the body with crowded unpaired fins. The role of this crowding was mentioned above as an “oar” that gives acceleration to the fish when attacking.
Juveniles feed mainly freshwater shrimp. As they grow older, fish and even small animals, such as birds, are added to the arapaima’s diet. The arapaima spends most of its time at the bottom, so the main part of its menu consists of bottom fish. In general full picture about the nutrition of these huge fish no due to poor knowledge of the species.