Infection with Ligula intestinalis was found to be the main cause of fish mortality in Satarkhan Dam of East Azerbaijan Province. Zooplanktons, fish, water and water birds were sampled and studied for infestation with the parasite. We randomly sampled 100 copepods, fixed them in Chloridric Acid 0.01% for 3-4 minute until tissue became soft and colored by Logol. After washing the sample with distilled water, the parasites were separated and identified perevalance of infection was sixteen (1% male and 15% female Cyclops).

Background: Ligulae intestinalis is a parasitic cestode, which has the economic-health importance in fishery industries. The aim of this study was to determine the prevalence of this parasite in Mazandaran. The effects of habitat temperature and kind of pool (sandy-cement) were considered as well.Methods: In this study, 103 fish samples were obtained in all stages; the samples (male and female) were divided into 3 groups based on length of fish, temperature, origin of cultured fish, kind of pool, height from sea and sex. Macroscopic and microscopic observations were carried out in all stages of the parasite (PROCERCOID, plerocercoid and adult). Chi-square and Pearson’s double square tests (P<0.05) were conducted in order to evaluate the prevalence and determination of reliability in six sampling areas, respectively.Results: Total rate of the parasites were 9.7% in all groups. There was significant difference between parasitism rate and height of sea level, kind of pool (maximum in sandy pools) and high temperature. The multi analyses regarding to abovementioned three criteria also indicated meaningful difference between these criteria and parasitism rate. Seasonal conditions enhance the prevalence of ligulae intestinalis.Conclusion: Flexibility in parasite’s life cycle and choosing different hosts makes it challenging case in fishery industry; moreover its prevalence could be predicted according to environmental conditions so choosing the minimal at risk place for salmonids farming. Further studies are recommended for evaluating the problems in fish fertility and probable risk for infected fish consumers.