Temporary pools are unstable environments formed by river flooding and rainfall. They host a variety of species, such as Mimagoniates lateralis, a Vulnerable fish typically found in streams, but not studied in temporary habitats yet. This study aimed to analyze the diet of M. lateralis in temporary pools of the Atlantic Forest. A total of 86 individuals were collected between January and December 2024, measured, dissected, and analyzed for feeding habits. Immatures individuals predominated, and males were larger than females. The diet was mainly by allochthonous items categorized as occasional, classifying the species as an opportunistic generalist, reinforcing the role of temporary pools as potential natural nurseries and highlight the importance of preserving riparian vegetation.