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Arapaima

life science Maturity 11-13 Next article →

The arapaima is a massive genus of bonytongue fish native to South America.

Arapaima-full
Arapaima-full

These giants inhabit the Amazon and Essequibo basins. They are among the largest freshwater fish on Earth. Many people call them pirarucu, a name from the Tupi language meaning "red fish."

Arapaima close-up
Arapaima close-up

In Colombia and Venezuela, they are known as sabalo. Because of their size and importance, they are vital to local food systems. However, they face threats from habitat loss and overfishing. In some tropical regions outside their native range, they are even considered invasive species.

The physical structure of the arapaima is built for both strength and movement.

Arapaima gigas scales 3860
Arapaima gigas scales 3860

They have a sleek, torpedo-shaped body with large, blackish-green scales. These scales feature bright red markings. The scales are highly advanced, consisting of a hard, mineralized outer layer. Beneath this layer are several layers of collagen fibers. These fibers use a Bouligand-type arrangement, similar to the structure of plywood. This design allows the scales to be tough yet flexible. This mechanism protects the fish while it remains mobile in the water.

To survive in oxygen-poor environments, the arapaima has developed a unique way to breathe.

Arapaima leptosoma 2009 G1
Arapaima leptosoma 2009 G1

While they have gills, they also possess a modified swim bladder. This bladder contains lung-like tissue that allows them to extract oxygen from the air. They also use a labyrinth organ, which is a structure rich in blood vessels. This organ opens into the mouth to help them breathe surface air. This adaptation is essential in oxbow lakes where dissolved oxygen may drop as low as 0.5 ppm. In these low-oxygen conditions, the arapaima becomes a top predator. It can easily hunt lethargic prey that cannot breathe as well.

Scientists have worked to clarify the taxonomy, or the classification, of these fish.

Arapaima gigas - Manila Ocean Park 01
Arapaima gigas - Manila Ocean Park 01

For a long time, researchers thought there was only one species. Today, FishBase recognizes four distinct species in the genus. These include A. agassizii, A. gigas, A. leptosoma, and A. mapae. Some species, like A. agassizii, are known mostly from old drawings. One type specimen was even lost during World War II bombings. Because these fish do not migrate, scientists believe more species may still be hidden in the Amazon Basin. Fossil evidence shows that similar species existed 23 million years ago in Colombia.

The scale of these fish is truly impressive.

Arapaima-full
Arapaima-full

An arapaima can reach lengths of over 3 meters, or about 10 feet. Some exceptional cases have even exceeded 2.6 meters in length. In terms of weight, they can reach 200 kg, which is roughly 440 pounds. Because of overfishing, it is now rare to find wild fish larger than 2 meters. However, in places like Thailand, fishermen still land specimens exceeding 150 kg. These massive sizes make them a significant part of the local ecosystem and economy.

Humans have developed many ways to interact with the arapaima.

Arapaima gigas at Beijing aquarium
Arapaima gigas at Beijing aquarium

The meat is a delicacy often called the "cod of the Amazon." Locals often salt and dry the meat to store it without refrigeration. Beyond food, the fish provides other resources. The bony tongue is used for medicine or to scrape guarana. The scales can even be used as nail files. Designers now use the skin as leather for shoes and handbags. Even the Department of Ucayali in Peru features the fish on its flag and seal.

Protecting the arapaima is a complex challenge for conservationists.

Arapaima shedd
Arapaima shedd

In the past, commercial fishing was very intense. Between 1918 and 1924, about 7,000 tons were taken annually. This led to a fishing ban in Brazil in 1996. A 2014 study showed that many populations were depleted or overexploited. However, new management strategies are working. In some areas, populations grew from 2,500 in 1999 to over 170,000 in 2017. This shows that sustainable management can help these ancient giants recover.

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🖼️ Images & Media (18)
File:Bandera de Ucayali.svg
Bandera de Ucayali.svg
File:Escudo Región Ucayali.svg
Escudo Región Ucayali.svg
File:Arapaima-full.jpg
Arapaima-full.jpg
File:MURAL - LA PESCA DEL PAICHE.jpg
MURAL - LA PESCA DEL PAICHE.jpg
File:Arapaima close-up.jpg
Arapaima close-up.jpg
File:Arapaima gigas at Beijing aquarium.JPG
Arapaima gigas at Beijing aquarium.JPG
File:Arapaima gigas scales 3860.jpg
Arapaima gigas scales 3860.jpg
File:Arapaima leptosoma 2009 G2.jpg
Arapaima leptosoma 2009 G2.jpg
File:F de Castelnau-poissonsPl25.jpg
F de Castelnau-poissonsPl25.jpg
File:Arapaima leptosoma 2009 G1.jpg
Arapaima leptosoma 2009 G1.jpg
File:F de Castelnau-poissonsPl26 Osteoglossum minus.jpg
F de Castelnau-poissonsPl26 Osteoglossum minus.jpg
File:Lycoptera reconstruction.jpg
Lycoptera reconstruction.jpg

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