The glochidia of freshwater mussels are obligatory parasites of fish. If glochidia attach successfully to an appropriate host, they become encysted, feed and develop. After metamorphosis, they drop off onto the substrate, and continue to develop as juveniles. Most studies have investigated the occurrence of glochidia on adult fish, whereas the potential of early life stages of fish as hosts has received little attention. Yet the larvae and early juveniles of fish, being abundant seasonally, may provide opportunities for glochidia. This study took advantage of routine sampling of fish larvae in the Edward/Kolety–Wakool River system, south-eastern Australia, during the spring–summer of 2018/19. We investigated if the early life stages of fishes are used as hosts for the glochidia of hyriid mussels; which species and life stages were parasitised, and the temporal and spatial occurrence of glochidia infections. Across the 20 study sites, glochidia were detected on fish from October 2018 – January 2019. Of the 5017 larvae and juveniles from nine species collected in light traps and drift nets, glochidia were found on 269 individuals from six native species. Glochidia were detected at 15 of the study sites, and spatial patterns in the relative abundance of glochidia observed. Our results suggest that the early life stages of at least some Murray-Darling Basin fishes act as hosts for glochidia and that routine sampling of them may be a useful way for detecting the presence and spawning of river mussels. The next phase of this research is to assess if the spatial variation in glochidia abundance observed on larval fish can be explained by the spatial distribution of adult mussels. It may be possible that sampling of larval fish for glochidia may be a cost-effective way of determining the location, relative abundance and biomass of adult populations in otherwise difficult-to-survey environments.