ABSTRACT While nephrocalcinosis (kidney stones) is uncommon in wild teleost fish, various environmental and nutritional factors could lead to its occurrence in aquacultured fish. This study presents the first documented case of kidney stones in aquacultured Brazilian sardine ( Sardinella brasiliensis ). During necropsy, eighteen hard, white kidney stones were found in the posterior kidney, with an average diameter of 3.71 mm and a total length of 16.8 mm. Morphological analysis revealed stones of different sizes and shapes, including elongated and irregular structures. This discovery enhances our understanding of pathological conditions in S. brasiliensis and underscores the importance of further research into the causes, prevalence and potential implications for fish health and fisheries sustainability.