Biological invasions impact many communities and ecosystems around the world. Thus, the detection of harmful species is particularly important. In this study, the occurrence of Peacock bass Cichla kelberi in the Brazilian Pantanal was registered. The main stream of the Paraguay River, the Padre Inacio stream and their connected lakes were sampled, in the Pantanal, Upper Paraguay River basin. Six specimens were sampled including three females at beginning of maturation. The high level of turbidity of the main channel of the Paraguay River is possibly restricting the dispersal of C. kelberi to other regions of the Pantanal. But, due to the voracious piscivory of this species and the impact had in other Neotropical regions, this record highlights that the occurrence of C. kelberi can be a new threat to one of the bestconserved wetlands in the world.