Arroyo Cuñapirú is a tributary stream of the Paraná River basin flowing through the subtropical province of Misiones, Argentina, near the town of Jardín América. This stream drains a landscape characterized by the dense Atlantic Forest of northeastern Argentina, a region recognized as one of the most ichthyologically diverse areas in South America. The Cuñapirú watershed sits at the intersection of major drainage systems — the Paraná, Uruguay, and Iguazú — contributing to an extraordinary level of fish endemism. The stream and its associated tributary, Arroyo Cuñapirú Chico, together form a small but biologically significant watershed within the southern middle Paraná drainage system.