摘要：The fisheries of bony fishes has an economic importance in southern part of Caspian Sea, but there are some reports about their pathogens in this area .EustrongyIides excisus a parasite (Nematoda: Dioctophymidae) can damage the muscles of bony fishes . So, consumers avoid buying the infected fish. Hence, the parasite can cause economic loss. In order to detennine the occurance and intensity of the parasite, a study has been carried out on twelve fish species (no=373) including Cyprinus carpio (no=42), Esox lucius (no=6t)) , Carassius auratus gibelio (no=42), Abramis brama orientalis (no=50) , Perca fluviatilis (no=36), Vimba Vimba persa (no=50) , Chalcalburnus chalcoides (no=50), Barbus capito (no=5) , Aspius aspius {no=5),Neogobius fluviatilis(no=14) , N.kessleri (no=12) and N.caspius(no=7). Common parasitology procedures were used for necropsy of the fishes and recovery of the parasite. Standard statistical computations (mean, Standard Deviation, range, prevalence and dominance) were calculated for the overall samples. Eustrongylides excisus (L) was isolated from Esox Iucius (prevaIence=5"/a, mean intensity = 5.33) and P. fluviatilis (prevalence= 33.3%, mean intensity= 1.5). The parasite was observed as coiled in cysts inside the muscles of these two fish species. The parasite was also isolated from the body cavity of Barbus capito, Aspius aspius and muscles, ovaries, body cavity, upon liver and testis of Neogobius fluvlatilis, Mkessleri and N.caspius. The Infection of Barbus cap.-‘ta, Asplus aspius, Neogobius fluviatilis, N.kessleri, N.casp.ius and perch (P. fluviafilis) is reported for the first time from Iran.
