The Amazon's giant seed-dispersing fish can breathe air and survive in acidic water

Nature · Published 3 October 2026 Swipe more like this →

In short: The tambaqui is a heavyweight of the Amazon, capable of reaching 44 kilograms and living for over 60 years. Beyond its impressive size, this freshwater giant acts as a vital forest gardener, consuming and dispersing seeds while navigating extreme environmental shifts that would kill most other fish species.

Native to the Amazon and Orinoco basins, the tambaqui is the heaviest characin in the Americas. Its survival strategy is remarkably flexible; when oxygen levels in its habitat drop, the fish can switch to breathing air using specialized vascularization in its gills and swim bladder. It also demonstrates exceptional resilience to water chemistry, withstanding acidic conditions as low as pH 3.0 and maintaining stable gut microbial communities even when migrating between nutrient-poor blackwater and nutrient-rich whitewater streams.

The tambaqui plays a critical ecological role as a seed disperser, functioning much like a bird of the forest. During the flood season, fruits and seeds can make up nearly the entire diet of the fish, with a single 10-kilogram specimen capable of carrying over 1 kilogram of seeds in its gut. These seeds are deposited across the flooded landscape, aiding forest regeneration. While it is a prolific disperser, its relative, the red-bellied pacu, is considered even more efficient because a higher percentage of seeds pass through its system undamaged.

Despite its ecological importance, the species faces significant pressure from overfishing. In Manaus, annual landings plummeted from approximately 15,000 metric tons in the 1970s to just 800 metric tons by 1996. Today, the tambaqui is a cornerstone of South American aquaculture, valued for its disease resistance and ability to thrive in low-oxygen environments. While it is sometimes hybridized with Piaractus species to improve cold-water tolerance, wild populations remain under threat, with many individuals currently caught being juveniles that have not yet reached maturity.

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