Arroyo Ñireco is a small, intimate stream tucked within the northern Neuquén province of Patagonia, Argentina. Born from Lago Lauquen Mallín at approximately 1,800 meters above sea level, the stream winds its way through 34 kilometers of classic Patagonian landscape before emptying into the Río Reñileuvu at around 987 meters elevation. Its name comes from the Mapudungun language of the indigenous Mapuche people — "ñire" referring to a native hardwood shrub tree, and "co" meaning water, making it roughly "River of the Ñire." Fed not only by its headwater lake but also by a series of mallines (boggy meadow springs) and small tributaries along its course, the Ñireco maintains a remarkably consistent flow throughout the fishing season. The stream runs entirely through the lands of Estancia Chochoi Mallín, giving it a private, exclusive character that keeps fishing pressure low and the experience intimate. Crystal-clear water year-round makes this a sight-fishing paradise, and its serpentine, narrow character through low-cut banks draped in shrubs and willows gives it the feel of a true spring creek — a hidden gem of northern Patagonia.