BACKGROUND: Brachygalaxias bullocki (Regan, 1908) is a small-sized freshwater fish species (41 to 46 mm) and endemic to Chile. Its biology has still various knowledge gaps, and its distribution range has been reduced in the last decade due to human intervention. FINDINGS: In this article, for the first time, its presence in forested wetlands of Chile (38°52' to 39°02' S) is documented. The presence of this species in these ecosystems is restricted to wetlands with permanent water regime and depths ranging from 15.7 to 83.5 cm. CONCLUSIONS: The physicochemical habitat conditions show important seasonal variations, suggesting that B. bullocki is resistant to a wide range of temperatures, as well as different levels of dissolved oxygen and conductivity.