"Fish deformities expose ‘collapse’ of Xingu River’s pulse after construction of Belo Monte Dam", 31 December 2025

...Today, almost 10 years after the start of operations, new adverse impacts from the Belo Monte dam continue to emerge. In 2025, the same monitoring group released a technical note describing visible physical changes in silver croakers (Plagioscion squamosissimus). The specimens they found had squat, oval and rounded bodies — very different from their normal elongated aspect, indicating spinal deformities.

Born and raised in the Xingu area, in the riverside village of Belo Monte, Sara Rodrigues Lima was one of the fisherwomen who found fish in these conditions and began documenting them in 2021. Since then, she has reported not only deformities and impaired growth but also the surprising prevalence of these problems. She estimates that four out of every 10 fish caught are affected, but the figures still need to be corroborated by further research...

Lima has become an active voice in the fight against the dam, operated by Norte Energia. Her photos and notes not only inform independent monitoring but have also led prosecutors from the MPF to file a lawsuit against the diversion of the Xingu’s flow to Belo Monte’s turbines. In 2025, during the COP30 climate summit in Belém, capital of the state of Pará, where the dam is also located, the prosecutors presented their view of ecosystem collapse to the public and the press, citing fish deformities as one of the indicators...

The first hypothesis is nutritional deficiency due to the change in the river’s food chains. Another possible cause is the replacement of an environment characterized by rapids that are unique to the area with one full of sediment, with warm, stagnant waters and, therefore, less available oxygen, which would affect the development of fish in their larval stage. It’s also likely that the water retained in the dam’s reservoir is contaminated with toxic substances such as mercury, which is known to cause deformities...

In response to Mongabay, Norte Energia says “the project was designed to generate a large amount of energy during the Amazonian winter, from December to May, and follow and respect the seasonality of the river in the remaining months of the year.” The company denies that the dam has created drought in the Xingu River, and that the phenomenon “occurs naturally”...

Norte Energia also denies any environmental changes linked to the dam that could have caused fish deformities, adding that it conducts “ongoing monitoring of environmental and fish quality in Belo Monte’s catchment area”...