<p>Amazonian stream fishes are often adapted to specific ecological niches, and certain species maintain consistent reproductive patterns even when environmental conditions change. This study aimed to determine whether closely related species sharing the same environmental conditions exhibit similar reproductive strategies. To this end, we conducted a Principal Coordinates Analysis (PCoA) on five reproductive traits of three electric fish species from the Eastern Amazon: <i>Gymnorhamphichthys rondoni</i> and <i>Hypopygus lepturus</i> (Rhamphichthyidae) and <i>Eigenmannia pavulagem</i> (Sternopygidae). We also evaluated the influence of local environmental variables on the monthly variation in gonadal maturation activity using regression models. The ordination results showed that closely related species (<i>G. rondoni</i> and <i>H. lepturus</i>) exhibited similar reproductive traits. Batch fecundity was the trait that most differentiated the Rhamphichthyidae species from <i>E. pavulagem</i>, which recorded the highest average batch fecundity (103 mature oocytes). Although all three species are batch spawners, <i>E. pavulagem</i> displayed two modal oocyte size groups, whereas the Rhamphichthyidae species had three to four. The regression models indicated that different environmental variables influenced the reproductive responses across species and sexes, with rainfall included in all models except those for <i>G. rondoni</i> and <i>E. pavulagem</i> males. Overall, the models explained between 40 and 64% of the monthly variation in the gonadosomatic index (<i>GSI</i>) for females. Our findings suggest that closely related species exhibit some degree of niche conservatism. Despite experiencing similar selective pressures, the three species occupy and exploit different microhabitats, resulting in distinct investments in the sharing reproductive strategy.</p>