Introduction: Parasites play important roles in ecosystems, but can also create disturbances in the composition of host fauna in anthropogenic environments.
Objective: Knowledge about these organisms can contribute to the conservation of diversity and environmental quality and prediction of disease risks.
Methods: Parasites were collected from fish hosts in the Doce River (Claro River Basin, Middle Paranaíba) in areas of a small hydropower plant, following specific protocol and identified in the laboratory.
Results: This is the first report of Riggia cryptocularis (Crustacea: Cymothoidae) parasitizing Hypostomus ancistroides, Leporinus friderici and Serrasalmus maculatus.
Conclusion: The presence of this parasite in three fish species during the same sampling period and the severity of mutilation in the host suggest that the dam may favor a possible outbreak of the parasite R. cryptocularis due to changes introduced in the environment by the establishment of this type of project
