 Reservoirs built in Brazil for water supply, irrigation and electricity generation have brought economic development but also altered natural hydrologic regimes, affecting habitat quality and biode dynamics. Fish species richness usually increases immediately after reservoir formation but decreases as they age. Dams promote discharge control, altering seasonal flood cycles. Most affected species are re-aphilix and long-distance migratory that require distinct habitats. Management actions such as fish passages, fishery control, and stocking have been taken to minimize dam impacts, but their results are questionable. The Piranha River basin in Brazil is the most affected by dams, with negative consequences on fisheries and ecosystem functioning. Suggestions for improving conservation of ikthia fauna include better management actions, monitoring, and restoration efforts. This article was authored by A. A. Augustino, F. M. Pellises, and L. C. Gomez. We are article.tv, links in the description below.