The nematode Camallanus corderoi infects the intestine of native fishes and introduced salmonids in southern Chile between 39°S and 41°S. Among the 4 most common and widely distributed species of copepods in freshwaters of the region that were challenged, only Mesocyclops araucanus (Cyclopoida) was susceptible to experimental infection with C. corderoi. At temperatures of 20 ± 1°C, free first-stage larvae of C. corderoi had reached the hemocoel by 4 hr after ingestion by the copepods. The first molting of larvae was observed on day 2 postinfection (PI). Unsheathed second-stage larvae were observed in the hemocoel at day 3 PI, and had molted by day 6. Unsheathed third-stage larvae were recovered on day 7 PI. Third-stage larvae had a tail with 3 conical processes and a buccal capsule composed of a single chamber with a basal ring and longitudinal ridges.