The aquaculture of Nile tilapia (Oreochromis niloticus) in cages has faced problems with invading golden mussels (Limnoperna fortunei), an exotic species that shows uncontrolled dissemination. A possible use of golden mussel flour as a fish feed ingredient is investigated in this study. The assessment as food ingredient includes the description of the raw material processing and the analysis of the performance of Nile tilapia, submitted to diets containing different proportions of golden mussel flour, substituting for the traditional source of calcium in fish feeds. The mussels were collected in a fish farm in the northwest of the State of São Paulo and processed in the laboratory. The diets were prepared with different mussel flour proportions (0, 0.35, 0.68, 1.35, and 2.69%). One hundred fifty Nile tilapia fingerlings weighing 4.69 g were distributed in 15 tanks of 150 L. Neither heavy metals nor total coliforms were detected in the analyses of the golden mussel. The chemical-bromatological composition of golden mussels presented 13.41% crude protein, 1.47% ether extract, 30.58% calcium, and 0.20% phosphorus. Golden mussel flour proved an excellent substitute for limestone, yielding similar results concerning the zootechnical variables and better results regarding body composition variables. Despite the successful use of golden mussel flour as a food ingredient, it may not be the final solution for the problems caused by the mollusk. In any case, controlling its dissemination in nature can be an efficient and sustainable method.