Ninety-six-hour static bioassays were conducted in the laboratory to determine lethal concentrations (96-h LC50) of copper and cadmium for curimatã (Prochilodus vimboides) and piauçu (Leporinus macrocephalus). The 96-h LC50 of copper were 0.047 and 0.090 mg L-1, and of cadmium 3.16 and 7.42 mg L-1 for curimatã and piauçu, respectively. Curimatã is a preferred indigenous species for toxicological studies in the Doce River basin due to its availability in the hatcheries of the region and high sensitivity to metals.