Brazil's aquatic biodiversity is under threat from a proposed law that aims to boost degraded fishery resources. If approved, the law — put forward by Nelson Meurer of the Brazilian National Congress — would allow the cultivation of non-native fish species in freshwater aquaculture cages, overriding the currently prohibited introduction of non-native species into Brazil.

The fish that would be introduced are tilapia and carp species, and other species that are potentially invasive in Brazil (J. R. S. Vitule et al. Fish Fish. 10, 98–108; 2009). If these were to escape, they would further disrupt native freshwater biodiversity, which is already compromised by dam construction and pollution.

Politicians should instead be creating mechanisms to preserve native fauna and ecosystem functions, helping to realize Brazil's potential as a model for biodiversity conservation in the spirit of next month's Rio+20 conference. Meeting socio-economic needs must have the backing of sound environmental research.