Predation by invasive salmonids threatens the conservation of the endangered Australian freshwater fish Macquarie perch (Macquaria australasica). Predation is difficult to detect visually because larval fish are rapidly digested. Here, we present PCR primers that will enable the detection of M. australasica from trace samples, removing the need to detect undigested larval fish to confirm predation. We tested these primers on DNA from all fish species present in an upstream section of the Cotter River, a key locality for the species. We demonstrate the primers to be species-specific, amplifying DNA from M. australasica only.