CONICET | Buscador de Institutos y Recursos Humanos

This study describes the reproductive strategy of the stream-dwelling catfish Hatcheria macraei in the Pichileufu River in Argentina. Gonadal maturity phases, classified on the basis of histological analysis, stages of gamete development and the frequency distribution of oocyte size, were correlated to macroscopic features of the gonads. Hatcheria macraei has a cystovaric ovary, asynchronic oocyte development and a lobular type testicle. Five oocyte and four spermatogenic stages were identified and related to macroscopic gonadal characteristics, making it possible to divide gonadal development into five phases for females and males. Mature oocyte diameter ranged from 922 to 1935 μm. Absolute fecundity in mature females varied from 115 to 480 oocytes. Hatcheria macraei has multiple spawns during a protracted reproductive season which extends from December to April. This, together with its small size, is characteristic of an opportunistic reproductive strategy, commonly found in species that inhabit adverse and unpredictable environments, such as the low order rivers of Patagonia.