On November 28, 2025, Roberto do Carmo Jesus, 53, hooked a massive pirarucú in the Marinheiro River, a tributary of the Rio Grande in São Paulo state. Weighing around 160 kilos and stretching 2.5 meters, the fish was too large to fit in his boat. Alone on the water, Roberto had to tow the giant catch to shore, where three men helped him lift it onto a scale.
The battle began when the pirarucú struck at the rod fitted with the thinnest line. The initial pull was sudden and forceful, threatening to snap the tackle. Over the next 45 minutes, Roberto carefully wore down the fish, using patience and skill to avoid losing it. The catch shattered his previous personal record of 115 kilos and yielded more than 100 kilos of fillets, which he later sold for more than 4,000 reais.
Changing Rules for an Invasive Species
The catch took on new significance amid government-backed efforts to manage pirarucú populations beyond the Amazon, where the fish is treated as invasive. In Rondônia, an operation in the Rio Cautário State Extractive Reserve removed about 18.9 tonnes of pirarucú in two phases between August and October 2026. The initiative reportedly generated around 180,000 reais for extractive workers while seeking to reduce the fish’s presence in the affected river system.
One fish removed in the Rondônia operation measured about 2.46 meters and weighed nearly 138 kilograms. The state environmental authority, Sedam, identified it as the largest pirarucú recorded in a conservation unit in Rondônia. The species is native to the Amazon, but in some non-Amazonian environments its presence is managed as an ecological concern. The Rondônia campaign shows how control efforts can reduce the population while generating income for local workers.
Unique Biology and Adaptation
The pirarucú stands out for its size and biology. As it matures, its swim bladder develops into a lung-like organ, making it an obligate air-breather. This adaptation lets the fish survive in oxygen-poor waters, but it still depends on aquatic environments for movement and survival. It can endure brief periods out of water if kept moist, but cannot live on land. Pirarucú can exceed two meters; some accounts put its potential length at about three meters and its weight at up to 200 kilograms.
In the species’ native Amazonian range, management can focus on conservation instead of removal. A community-based model introduced in the middle Solimões region in 1999 uses annual fish counts to set catch limits and protect the reproductive period. It has technical support from Instituto Mamirauá and approval from Ibama. In managed areas, the reported population growth rate is about 25% a year, while the average size of captured fish rose from 1.27 meters in 1998 to 1.80 meters in 2022.
Roberto's experience is not unique. Other anglers have reported encounters with giant fish, such as the great white shark known as Contender, which recently resurfaced in the Atlantic and drew attention for its size and migration patterns (see more on the Atlantic shark's journey).
Economic and Environmental Impact
With over 30 years of fishing experience and more than a hundred pirarucús caught, Roberto has seen firsthand how the species has spread beyond its original range. A catch of this size can bring large income, while the Rondônia operation shows that organized management can also channel revenue to local extractive workers. The ecological approach depends on context: in parts of the Amazon, community-led quotas support recovery; targeted removals are used where pirarucú is considered invasive.
Cases like Roberto's bring those economic and environmental questions into focus. The fish’s exceptional size is biologically plausible: the Rondônia operation recorded a specimen measuring 2.46 meters and weighing nearly 138 kilograms. Its 18.9-tonne removal effort also shows the scale of organized interventions outside the species’ native range, where environmental authorities aim to limit its presence in affected ecosystems.
