The pirarucu, a significant fish in the Amazon, has recently been declared an invasive species in the Madeira River, especially above the Santo Antônio dam in Porto Velho. This classification was officially implemented by the Brazilian Institute of Environment and Renewable Natural Resources (Ibama), which has authorized unlimited fishing of the pirarucu in this area. This means that both professional and artisanal fishermen can now capture and kill the fish without any restrictions on quantity, size, or season.

The decision to classify the pirarucu as an invasive species is closely tied to changes in environmental conditions within the river. Dr. Dayane Catâneo, a specialist in Biodiversity and Biotechnology, notes that the fish's expansion into new areas of the river correlates with these ecological shifts. Historically, the pirarucu thrived primarily downstream of the Santo Antônio waterfall, where natural conditions were more conducive to its survival. However, alterations in the ecosystem have allowed the species to spread into areas where it was previously less common.

This development raises important questions about biodiversity and ecological balance in the Amazon. By permitting unlimited fishing of the pirarucu, authorities aim to manage its population, but there are potential risks to the ecological fabric of the river. The long-term consequences of removing such a prevalent species from the ecosystem could be significant, possibly impacting other native species and the overall health of the river environment.