In parasitologic survey on sturgeon fish in Shahid-Beheshti farm, the metacercaria of Diplostomum spathaceum were seen in the lens of fish fingerlings. The prevalence of infestation was 22 percent. The infestation with this parasite was one of the reasons of body lose weight and mortality. Observations showed that the ratio of the body weight loses directly depend on the number of metacercaria. During the study two different family of intermediate hosts include; Limneidae and Physidae were identified. The frequency of Physidae is more than Limneidae......