Açude Engenheiro Ávidos, also known locally as the Piranhas reservoir, is a public water body situated in the state of Paraíba, Brazil, in the semi-arid northeastern region of the country. Located at approximately 7°00′44.3″S, 38°27′23.8″W, this reservoir is part of the broader network of public açudes (reservoirs) that serve as vital water resources in the Paraíba interior. Like many reservoirs in the northeastern Brazilian sertão, it sits within a landscape shaped by the caatinga biome — a unique dryland ecosystem characterized by thorny scrub vegetation, rocky terrain, and a climate defined by pronounced wet and dry seasons. The reservoir draws water from the surrounding drainage network, including nearby riachos (streams) such as Riacho Pau Brasil, Riacho Piancó, Riacho do Braz, Riacho Baiao, Riacho São Francisco, Riacho Sêco, Riacho Traíras, Riacho Jaguaribara, and Riacho Bragantino, making it a confluence point for regional surface water flows. As a public açude in Paraíba, it represents both a community water supply and a recreational fishing resource for local residents and visiting anglers alike.