---
title: "What the sources say about the Arapaima | AnimalTracks.wiki"
description: "57 claims from the Arapaima profile, each beside the words of the source that backs it."
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# What the sources say about the Arapaima (*Arapaima gigas*)

> 57 claims from the Arapaima profile, each beside the words of the source that backs it. A "..." marks a cut in a quote and [brackets] an insertion.

Profile: [Arapaima](https://animaltracks.wiki/animals/arapaima/)

## Arapaima. Smithsonian's National Zoo and Conservation Biology Institute.

https://nationalzoo.si.edu/animals/arapaima

| The page says | The source says |
| :--- | :--- |
| can reach three meters | reaching up to 440 pounds (200 kilograms) and 10 feet (3 meters) in length (note: 3 meters written as 'three meters' for the tagline.) |
| breathes air through a lung-like swim bladder | it takes in air using a modified swim bladder that opens into the fish's mouth and acts as a lung |
| Its gills are so small that it takes in air using a modified swim bladder that opens into its mouth and acts as a lung | Its gills are so small that it takes in air using a modified swim bladder that opens into the fish's mouth and acts as a lung. |
| It lives in slow-moving, typically oxygen-poor rivers of the Amazon River basin floodplain in Brazil, Peru and Guyana | The arapaima is found in Brazil, Peru and Guyana. They live in the slow-moving and typically oxygen-deficient rivers of the Amazon River basin floodplain. |
| Out of the water, an arapaima can survive as long as 24 hours | It can survive as long as 24 hours outside the water. |
| Known in Brazil as pirarucu, a Tupi word that translates roughly as "red fish," and in Peru as paiche | In Brazil, they are known as "pirarucu," a word from the Tupi language, which translates roughly as "red fish." In Peru, they are known as "paiche." |
| the arapaima is possibly the largest freshwater fish in the world | The arapaima is possibly the largest freshwater fish in the world |
| reaching up to 440 pounds (200 kilograms) and 10 feet (3 meters) long, though 200 pounds (90.7 kilograms) and 7 to 8 feet (2.2 to 2.4 meters) is more common | reaching up to 440 pounds (200 kilograms) and 10 feet (3 meters) in length. However, sizes of 200 pounds (90.7 kilograms) and 7 to 8 feet (2.2 to 2.4 meters) in length are more common. |
| It can live up to 20 years | The arapaima can live for up to 20 years. |
| An arapaima feeds by opening its large mouth to create a vacuum that pulls in nearby food | by opening their large mouths they create a vacuum that pulls in nearby food objects |
| It eats mostly fish but is also known to eat fruit, seeds, insects, and birds and mammals found on the surface of the water | the arapaima eats mostly fish but is also known to eat fruits, seeds, insects, birds and mammals found on the surface of the water. |
| it can use short bursts of speed to attack prey hitting the surface | They can also use short bursts of speed to attack potential prey hitting the surface of the water. |
| sharp, bony teeth, together with the teeth on the roof of its mouth, let it disable and shred its prey | Their tongues and sharp, bony teeth, combined with the teeth on the roof of their palates, allow them to debilitate and shred their prey. |
| Its gills are so small that it takes in air using a modified swim bladder that opens into its mouth and acts as a lung. | Its gills are so small that it takes in air using a modified swim bladder that opens into the fish's mouth and acts as a lung. |
| It can stay underwater for 10 to 20 minutes at a time | This fish can breathe air and stay submerged for 10-20 minutes at a time. |
| it can survive as long as 24 hours out of the water | It can survive as long as 24 hours outside the water. |
| Slow-moving, typically oxygen-poor rivers of the Amazon River basin floodplain in Brazil, Peru and Guyana | The arapaima is found in Brazil, Peru and Guyana. They live in the slow-moving and typically oxygen-deficient rivers of the Amazon River basin floodplain. |
| Mostly fish, but also known to eat fruit, seeds, insects, and birds and mammals found on the surface of the water | the arapaima eats mostly fish but is also known to eat fruits, seeds, insects, birds and mammals found on the surface of the water. |
| A lung-like swim bladder for breathing air | a modified swim bladder that opens into the fish's mouth and acts as a lung |
| a fish of up to 200 kilograms | reaching up to 440 pounds (200 kilograms) and 10 feet (3 meters) in length |

## Arapaima gigas (arapaima). Animal Diversity Web, University of Michigan.

https://animaldiversity.org/accounts/Arapaima_gigas/

| The page says | The source says |
| :--- | :--- |
| which means it has to breathe air: it needs to surface every 10 to 20 minutes | it is an obligate air breather that needs to surface every 10-20 min (note: Smithsonian agrees: 'stay submerged for 10-20 minutes at a time'.) |
| and in floodplain lakes and flooded forest | A. gigas is found in several different types of habitat, such as the floodplain lakes of this region ... and the varzea or forest. (note: 'flooded' follows the Smithsonian: 'When the rivers overflow, fish can be dispersed into the surrounding forest for miles'.) |
| Its bony or toothed tongue | A. gigas has a bony or toothed tongue |
| It is bony or toothed, a feature that sets apart the fish in its order, the Osteoglossiformes | A. gigas has a bony or toothed tongue, which is the source of the title osteoglossomorph and a distinguishing character of those species in the order Osteoglossiformes |
| People have often used the pirarucu's bony tongue to scrape cylinders of dried guarana, an ingredient in a drink | the pirarucu's bony tongue is often used to scrape cylinders of dried guarana, an ingredient in a beverage (note: Past tense because ADW's account dates from 2003.) |
| plus floodplain lakes and flooded forest | A. gigas is found in several different types of habitat, such as the floodplain lakes of this region ... and the varzea or forest. |
| a bony or toothed tongue | A. gigas has a bony or toothed tongue |
| dangerLevel: Low | There are no known adverse effects towards Homo sapiens. (note: Settle #396: Medium to Low; no source in the pack describes harm to people.) |
| needs to surface every 10 to 20 minutes to breathe | it is an obligate air breather that needs to surface every 10-20 min |

## Lin et al. (2011). Mechanical properties and the laminate structure of Arapaima gigas scales. Journal of the Mechanical Behavior of Biomedical Materials.

https://doi.org/10.1016/j.jmbbm.2011.03.024

| The page says | The source says |
| :--- | :--- |
| made of thin layers of collagen fibers | internal lamellae with thickness of 50-60 μm each and composed of collagen fibers |
| The fibers in each layer line up, but their direction changes from layer to layer, a twisted-plywood pattern called Bouligand stacking | The alignment of collagen fibers is consistent in each individual layer but varies from layer to layer, forming a non-orthogonal plywood structure, known as Bouligand stacking. (note: 'twisted' follows mechanical-2013: 'Bouligand-type (twisted plywood)'.) |
| In hardness tests, the outer layer scored 550 megapascals (a unit of pressure), nearly three times the 200 megapascals of the inner layers | The micro-indentation hardness of the external layer (550 MPa) is considerably higher than that of the internal layer (200 MPa) (note: 'nearly three times' is 550/200 = 2.75.) |
| The scales help protect this big fish against predators such as the piranha | The Arapaima gigas scales play an important role in protecting this large Amazon basin fish against predators such as the piranha. |
| Each has a mineralized outer layer over thin inner layers of collagen fibers | They have a laminate composite structure composed of an external mineralized layer and internal lamellae with thickness of 50-60 μm each and composed of collagen fibers |
| The fibers line up within each layer, but their direction changes from layer to layer, a plywood-like pattern called Bouligand stacking | The alignment of collagen fibers is consistent in each individual layer but varies from layer to layer, forming a non-orthogonal plywood structure, known as Bouligand stacking. |
| In hardness tests the outer layer scored 550 megapascals, nearly three times the 200 megapascals of the inner layers | The micro-indentation hardness of the external layer (550 MPa) is considerably higher than that of the internal layer (200 MPa) (note: 'nearly three times' is 550/200 = 2.75.) |

## Zimmermann et al. (2013). Mechanical adaptability of the Bouligand-type structure in natural dermal armour. Nature Communications.

https://doi.org/10.1038/ncomms3634

| The page says | The source says |
| :--- | :--- |
| wears scale armor that resists piranhas | resist predation by piranhas through the strength and toughness of their scales, which act as natural dermal armour |
| Arapaima resist attacks by piranhas thanks to their scales, which act as natural armor | resist predation by piranhas through the strength and toughness of their scales, which act as natural dermal armour |
| Each scale has a hard, mineralized outer shell around a softer core | Arapaima scales consist of a hard, mineralized outer shell surrounding a more ductile core. (note: 'softer' rests on mechanical-2011's hardness figures (outer 550 MPa, inner 200 MPa), claimed below.) |
| In lab tests that pulled on scales, most of these layers turned toward the pull and stretched or slid, making the scale tougher and helping it avoid cracking | during mechanical tensile tests ... most lamellae reorient towards the tensile axis and deform in tension through stretching/sliding mechanisms ... thereby enhancing the scale's ductility and toughness to prevent fracture. |
| scale armor that resists piranhas | resist predation by piranhas through the strength and toughness of their scales, which act as natural dermal armour |

## Brauner et al. (2004). Transition in organ function during the evolution of air-breathing; insights from Arapaima gigas, an obligate air-breathing teleost from the Amazon. Journal of Experimental Biology.

https://doi.org/10.1242/jeb.00887

| The page says | The source says |
| :--- | :--- |
| one of the most obligate air-breathing fishes alive | Arapaima gigas is one of the most obligate extant air-breathing fishes (note: 'alive' renders 'extant'.) |

## Du et al. (2019). The genome of the arapaima (Arapaima gigas) provides insights into gigantism, fast growth and chromosomal sex determination system. Scientific Reports.

https://doi.org/10.1038/s41598-019-41457-x

| The page says | The source says |
| :--- | :--- |
| gets up to 95 percent of its oxygen by breathing air | As an obligate air-breathing fish obtaining up to 95% of its oxygen uptake by breathing (note: 'breathing' in the source is air breathing: the same sentence calls it an obligate air-breathing fish.) |
| Breathing air lets it tolerate extremely low oxygen levels in the water | As an obligate air-breathing fish obtaining up to 95% of its oxygen uptake by breathing, it is able to tolerate extremely low oxygen levels in the water (note: The source's 'As an obligate air-breathing fish ... it is able to' is the link that 'lets' renders.) |
| In its first year a young arapaima can reach 10 to 15 kilograms, among the fastest growth rates recorded in fish | During the first year, juvenile arapaima exhibits the fastest growth rates recorded in fish, reaching weights between 10 to 15 kg |

## Campos-Silva & Peres (2016). Community-based management induces rapid recovery of a high-value tropical freshwater fishery. Scientific Reports.

https://doi.org/10.1038/srep34745

| The page says | The source says |
| :--- | :--- |
| Because an arapaima comes to the surface often to breathe air, it is easier to spot and count directly | thereby frequently coming to the surface to breathe air, which facilitates direct sightings and counts |
| Along Brazil's Juruá River, up to 20 trained fishermen per lake watched and listened for arapaima breathing | Along the Juruá, this technique involved the collaborative participation of up to 20 previously trained and highly experienced arapaima fishermen per lake, who could detect air-breathing arapaima on the lake surface through both visual and acoustic cues |
| A 2016 study of 83 oxbow lakes along about 500 kilometers of the river | across 83 oxbow lakes monitored along a ~500-km section of the Juruá River of Western Brazilian Amazonia (note: 2016 is the paper's publication year (reference metadata).) |
| protected lakes, which local communities manage and close to fishing boats | Protected lakes are managed by local communities primarily as stock recovery and arapaima management sites, and exclude both commercial and subsistence fishing boats. |
| held 304.8 arapaima on average, compared with only 9.2 in open-access lakes | Annual population counts showed that protected lakes on average contained 304.8 (±332.5) arapaimas, compared to only 9.2 (±9.8) in open-access lakes. |
| The counts went to IBAMA, Brazil's natural resources agency, which then authorized each lake a harvest of up to 30 percent of the adults counted, meaning fish longer than 1.5 meters | the census data are forwarded to IBAMA (Brazilian Natural Resources Agency), which then authorizes a lake-specific harvest quota of up to 30% of all adults (>1.5 m in length) counted |
| protected lakes could earn each community an average of US$10,601 a year, if the rules were followed and the full quota was caught | Protected lakes could derive total fishing revenues from arapaima stocks averaging US$10,601 ... every year, provided that full compliance with management rules takes place and total allowable catches (TACs) are harvested (note: A modelled estimate per community (the abstract: 'average annual revenue of US$10,601 per community'), conditional on full compliance and the full quota.) |
| An arapaima comes to the surface often to breathe air, which makes it easier to spot and count directly | thereby frequently coming to the surface to breathe air, which facilitates direct sightings and counts |
| a 2016 study found that protected lakes held 304.8 arapaima on average, compared with only 9.2 in open-access lakes | Annual population counts showed that protected lakes on average contained 304.8 (±332.5) arapaimas, compared to only 9.2 (±9.8) in open-access lakes. (note: 2016 is the paper's publication year (reference metadata).) |
| Brazil's natural resources agency, IBAMA, used the counts to authorize each lake's harvest quota | the census data are forwarded to IBAMA (Brazilian Natural Resources Agency), which then authorizes a lake-specific harvest quota of up to 30% of all adults (>1.5 m in length) counted |

## Arapaima gigas. The IUCN Red List of Threatened Species 1996: e.T1991A9110195.

https://doi.org/10.2305/iucn.uk.1996.rlts.t1991a9110195.en

| The page says | The source says |
| :--- | :--- |
| The IUCN Red List classes the arapaima as Data Deficient | IUCN Red List category: Data Deficient (DD). Arapaima gigas (Schinz, 1822), IUCN taxon 1991. (note: Current category from GBIF's copy of the Red List.) |
| based on an assessment made in 1996 | IUCN Red List category: Data Deficient (DD). Arapaima gigas (Schinz, 1822), IUCN taxon 1991. (note: 1996 is the cited assessment's own year, in its DOI (iucn.uk.1996.rlts.t1991a9110195) and title, which audit:sources checks against Crossref; the taxon id 1991 matches GBIF's. Hand check: that no later assessment exists.) |