Abstract
Fisheries play a crucial role in aquatic ecosystems, a resource with ecological and economic importance. Measuring parasite prevalence is necessary to assess these fish species' health and well-being. Within the Sistan region, this study sought to estimate the prevalence and intensity of infection with plerocercoid Ligula intestinalis (L. intestinalis) in seven fish species and identify factors such as fish weight, seasonality, and fishing location that might influence infection rates. 2800 fish from seven species were obtained in the Sistan region throughout four seasons. Fish samples from three weight categories (<200gr, 200-400gr, 400gr<) were examined parasitologically. Ligula intestinalis was detected in 96/2800 (3.4%) of fishs. There was a variation in prevalence among fish species. Alburnus charusini (A. charusini), Hypophthalmichthys molitrix (H. molitrix), Hypophthalmichthys nobilis (H. nobilis), and Schizocypris altidorsalis (S. altidorsalis) showed no infection. Schizothorax zarudnyi (S. zarudnyi) showed a prevalence of 1.5% (6/400), Cyprinus carpio (C. carpio) 15% (60/400), and Ctenopharyngodon idella (C. idella) 7.5% (30/400). It was found that infection prevalence was significantly influenced by fish weight in C . carpio and C . idella. A higher prevalence was found in fish with lower weight. Infection rates significantly fluctuated with season across species, but fishing locations had no significant difference. The present study highlights the significant prevalence of L. intestinalis infections in fish populations within Iran's Sistan region, underscoring the need for ongoing monitoring and research to inform effective fishery management strategies. Future studies should focus on long-term monitoring efforts and consider the broader global context of fish parasitology to understand parasite-host interactions better and inform conservation measures worldwide.