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A total of 394 (255 males,139 females) live freshwater crayfish Astacus leptodactylus from four stations of Aras reservoir in West Azarbaijan Province (North-Western Iran) were studied during the winter until early autumn of 2009 for the presence of parasites, Epibionts and Fungal agents. Parasitological surveys were carried out on gills exoskeleton and internal organs, mycological examinations on the exoskeleton (the legs, abdominal cuticle and the eggs). 9 epibionts and parasites peritrich protozoans including :Cothurnia sieboldii (68.5%), Zoothamnium spp. (56.6%), Vorticella similis (45.6%), Chilodonella spp. (0.5%), Podophrya fixa (7.8%), Epistylis chrysemidis (53.2%), Pyxicola annulata (66%), Opercularia articulata (19.8%), Tetrahymena pyriformis (0.5%) were recorded. From Metazoan parasites group, Branchiobdella kozarovi (71%) as the first observation was the only parasite recorded from exoskeleton with prevalence (100%) during spring and summer of the study year. Infected gills were heavily damaged with Aeolosoma hemprichi (Annelid) in winter with 90% prevalence. Other Epibiont fouling organisms such as Rotatoria free living Nematods were observed in this survey. Furthermore, on the mycotic agents identified Penicillium expansum Aspergillus flavus Alternaria sp. Fusarium sp. and  Saprolegnia sp. were isolated in IM media and identified with slides cultured from cuticular melanized lesions and eggs of infected specimens. This is the first investigation on epibionts, parasites and fungal organisms of the endemic crayfish in Aras reservoir, Iran.

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  Various parasite species were found in Carassius carassius including Diplostomum spathaceum, Dactylogyrus sp.,Gyrodactylus sp. Ichthyophthirius multifiliis and Trichodinia sp . They were found in four rivers in West Azerbaijan Province (North-Western Iran) . A total of 207 live Carassius carassius from four rivers including Aras (72) Zariyneh (42) Nazlo (58) and Barandoz (35) were studied. Parasitological surveys were carried out on gills and external organs. The results showed that Diplostomum spathaceum (70.83%) Dactylogyrus sp. (38.88%) Gyrodactylus sp. ) 22.22%) Ichthyophthirius multifiliis (48.61%) Trichodinia sp. (8.33%) Chilodonella sp. (12.50%) and Argulus sp. (76.19%) were found in fish from Aras Rive so that the result showed, Spathaceum (63.79%) Dactylogyrus sp. (36.20%) Gyrodactylus sp. (25.86%) Ichthyophthirius multifiliis (44.82%) Trichodinia sp. (18.96%) Chilodonella sp. (12.06%) and Argulus sp. (6.89%). Argulus prevalence was greater in Barandoz River while Chilodonella in Zariyneh rud River . In Barandoz River, Diplostomum spathaceum (65.71%) Dactylogyrus sp. (37.14%) Gyrodactylus sp. (22.85%) Ichthyophthirius multifiliis (31.42%) Trichodinia sp. (25.71%) Chilodonella sp. (8.57%) and Argulus sp. (5.71%) were reported, respectively. Finally, in Zariyneh rud river, the followings have been reported: Diplostomum spathaceum (76.19%) Dactylogyrus sp. (21.42%) Gyrodactylus sp. (14.28%) Ichthyophthirius multifiliis (52.38%) Trichodinia sp. (23.80%) Chilodonella sp. (14.28%) and Argulus sp. (7.14%). It should be noted that prevalence , intensity and host parasite relationship will be discussed in details in this article.

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The Astacus leptodactylus specimens were collected from four sites of Aras reservoir, North-West of Iran and examined for the epibionts during 2009. Protozoan epibionts from ciliophora (one genus and seven species) and tracheophyta were isolated from the cuticular surface of different body parts of narrow-claw crayfish, A.leptodactylus. Seasonal prevalence of infestation was determined in 394 individuals of A.leptodactylus. The facultative ciliate Tetrahymena pyriformis was identified on the gills and gill haemocoel with 0.5% prevalence. Futhermore , epibiont fouling organisms such as Epistylis chrysemidis (52.3%) Vorticella similis (45.9%) Cothurnia sieboldii (68.5%) Pyxicola annulata (66%) Chilodonella spp.(0.5%) Zoothamnium intermedium(57.1%) Opercularia articulate (20.6%) and Podophrya fixa (8.6%) were also isolated from 13 body parts of A.leptodactylus. The presence of Chilodonella infestation is the first record of this genus on freshwater crayfish species. The comparison of biometrical data of the epibionts showed no significant differences in prevalence of seasonal infestation between sampling sites. The current work represents the first documentation for the presence of protozoan epibionts on A.leptodactylus in Aras Reservoir, Iran.