This study analyzed the variation of the parasite infracommunities and their relationship with the diet and spatial distribution of the clingfish Sicyases sanguineus during its ontogeny. In total, 154 clingfish were collected from the intertidal and the upper subtidal zone of Pacific Ocean along the central Chilean coast. A wide range in body length (1.4–34.5 cm) was observed, including juvenile and adult specimens. Eleven parasite species were found in the clingfish, i.e., 2 Copepoda, 2 Hirudinea, 1 Monogenea, 5 Digenea, and 1 Cestoda. The prevalence, total abundance, Brillouin's diversity index, and the infracommunity species richness increased with fish body length. The parasite communities, the diet, and the spatial distribution changed during clingfish ontogeny, specifically between juveniles (<20 cm body length [BL]) and adults (>20 cm BL). When fish reached a 20-cm BL, a considerable increment in abundance and species richness of parasites was observed; this coincided with an increase in the number of prey items in the diet and with a change of the fish from the intertidal into the subtidal zone. Therefore, the ontogeny of S. sanguineus is important for the variation of parasite infracommunities, which also was associated with dietary and spatial distribution shifts of this fish.