American Oceans

The Biggest Fish in the Amazon River

close up of an arapaima swimming

The Amazon River, known for its incredible biodiversity, is home to some of the largest freshwater fish species in the world. As one of the most important ecosystems on the planet, the Amazon River supports numerous fascinating creatures, including the largest fish found in this vast body of water. This article will explore the biggest fish in the Amazon River and their remarkable adaptations to survive in this diverse environment.

The Arapaima gigas, commonly known as the pirarucu or paiche, is recognized as the largest freshwater fish in the Amazon River. This enormous fish can reach lengths of up to 9.8 feet (3 meters) and weigh over 400 pounds (200 kilograms). The Arapaima is known for its unique ability to breathe air, allowing it to survive in the low-oxygen conditions often found in the Amazon and Araguaia-Tocantins River basins. Additionally, its aggressive feeding behavior has earned the Arapaima gigas a reputation as one of the region’s top predators.

Another noteworthy contender for the title of the biggest fish in the Amazon River is the Piraiba catfish (Brachyplatystoma filamentosum). The Piraiba can grow up to 12 feet (3.6 meters) in length and weigh up to 450 pounds (204 kilograms). These massive catfish can be found throughout the Amazon Basin, where they feed on a diet primarily consisting of other fish and even small mammals. Both the Arapaima gigas and the Piraiba catfish are vital components of the Amazon River ecosystem, contributing to its rich biodiversity and global significance.


arapaima in the water

The Arapaima gigas, also known as the pirarucu, is a large fish native to the Amazon Basin. As one of the biggest freshwater fish species in the world, the Arapaima can grow up to 3 meters in length and weigh up to 200 kg. They are characterized by their elongated bodies, large scales, and wide mouths. The scales of the Arapaima are particularly unique, offering a high degree of protection from predators, as they are not only large but also have a strengthened layer of collagen fibers.

Arapaimas have a special organ called the labyrinth organ that helps them breathe in low-oxygen environments by allowing them to extract oxygen directly from the air. This is an adaptation to life in the Amazon Basin, especially in floodplains where oxygen levels in the water can fluctuate.

Behavior and Habitat

arapaima swimming underwater

The Arapaima inhabits primarily freshwater environments, such as rivers, lakes, and floodplains in the Amazon River Basin. The fish are known for their solitary nature, being mostly found individually or in small groups. They have a strong preference for areas with clear or white water, abundant vegetation, and adequate food sources.

Arapaimas feed on smaller fish, crustaceans, and even birds or small mammals that venture near the water. During the dry season, the Arapaima can be found in deeper waters; however, they tend to migrate laterally to shallower water during the flooding season as they search for prey and procreate.

Threats and Conservation Efforts

an arapaima underwater

Unfortunately, the size and unique biology of the Arapaima make them a target for overfishing. In addition to overfishing, the Arapaima also faces risks due to habitat loss and degradation, as well as illegal fishing. The combined impact of these factors has led the Arapaima to be listed as vulnerable to extinction according to the International Union for Conservation of Nature (IUCN).

Conservation efforts for the Arapaima primarily focus on the implementation and enforcement of sustainable fishing practices, community-based management, and raising awareness about the ecological and economic value of the species to the Amazon Basin. Additionally, research has been conducted on the rearing and production chain of the Arapaima, aiming to better understand how the industry can adapt and contribute to the protection of the species.

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