The northwestern region of Argentina has several gaps in ichthyogeographic knowledge and there are still bodies of water without records of the species that inhabit them. When planning mitigation projects or conservation or management actions, little knowledge of the biology of a species presents itself as a restriction. Therefore, the objective is to know the reproductive biology of the torrent catfish (H.macraei) in the Natural Protected Area La Ciénaga, San Juan, with the purpose of generating basic information as a tool for the future management of these populations. The torrent catfish, Hatcheria macraei (Girard, 1855) is a Siluriformes that belongs to the Trichomycteridae family, it is a rheophilic and phototactic negative species, which is characterized by living in cold and well-oxygenated waters with sandy and rocky substrates. In a period of one year, fecundity, reproductive potential, minimum reproductive size were determined, sexual dimorphism was evaluated, and the state of gonadal development was described. It was determined that the species presents an opportunistic strategy, presenting a prolonged reproduction period from October to November. [ABSTRACT FROM AUTHOR]