The presence of small trout together with fairy shrimp (Chirocephalus diaphanus) in isolated corrie lakelets in the French Pyrenees suggests that the fish might be agents of dispersal of the shrimp, if resting eggs could survive ingestion and freezing. Resting eggs in ovigerous females of Chirocephalus diaphanus can pass through the digestive tract of a trout and be subsequently frozen without losing their viability. Subsequently fecal pellets were collected from each fish. The gut passage time of C. diaphanus eggs were up to 4 days. Resting eggs recovered from fecal pellets were counted, frozen and then incubated. Hatching of nauplii began after 32 days, and 50.9% (sd. 29.4) hatched over the following 7 days. Ovigerous females of lab cultured C. diaphanus were administered to four trout Salmon trutta kept in separate tanks. Therefore, fish can aid upstream dispersion of these fairy shrimp.