The larvae (or glochidia) of freshwater mussels in the Order Unionida are obligatory parasites of fish. If glochidia attach successfully to an appropriate fish host, they become encysted, feed and develop. After metamorphosis, they will drop off onto the substrate, where they will 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 to be hosts has received little attention. The larvae and early juveniles of fish, being abundant seasonally, may provide opportunities for glochidia. This study took advantage of larval fish sampled as part of monitoring in the Edward/Kolety-Wakool River system during the spring-summer of 2018/19 and aimed to determine: 1) if the early life stages of fishes are used as hosts for the glochidia of hyriid mussels; 2) which species and life stages were parasitised, and 3) the temporal and spatial occurrence of glochidial infections. Mussel glochidia were detected on larval and juvenile fish from early October 2018 to late January 2019. Of the 5017 larvae and juveniles from nine fish species collected in light traps and drift nets, glochidia were found on 269 individuals from six species, including Murray cod, carp gudgeons and Australian smelt. Glochidia were present on larval Murray cod, and late-stage larvae and juveniles of carp gudgeons. Glochidia occurred most frequently around the mouth of Murray cod, around the mouth and caudal fin of Australian smelt, but were relatively evenly distributed across multiple body parts of carp gudgeons. Our results suggest that the early life stages of at least some Murray-Darling Basin fishes act as hosts for glochidia, and monitoring of glochidia on fish larvae may be a useful way of detecting the presence and spawning of river mussels.