Te Journal of Advances in Parasitology Continued Publication - 2022 | Volume 9 | Issue 1 | Page 1 INTRODUCTION G arra rufa (Heckel, 1843) commonly known as doc- tor fsh, are freshwater cyprinid species that natural- ly inhabit river basins, muddy streems, ponds and lakes in Eurasia. Tey are widely used in the health and beauty industries at the spa center for ichthyotherapy. Te spread areas of G. rufa were reported in Iraq, Iran, some coast- al rivers in southern Turkey and northern Syria. G. rufa might poses a potential risk to customers or ornamental and native fsh with zoonotic pathogens. Zoonotic agents could be transmitted not only directly from afected fsh, but also indirectly through water (Bhattacharya, 2016). Yellow spot disease is a common fsh parasitosis. Tis trem- atode has a very economic importance because of dam- age to fsh carcasses depending on white-yellowish nod- ules (Sutili et al., 2014). In addition to Clinostomum spp. is a fsh-borne zoonotic parasite responsible for Halzoun syndrome in humans who consume raw or undercooked freshwater fsh that infected by metacercariae (Kifune et al., 2000; Park et al., 2009; Sutili et al., 2014). Adult forms of digenean family Clinostomidae Lühe, 1901 were found in the mouth, esophagus and pharynx of fsh-eating birds, reptiles. Te frst intermediate hosts are freshwater snails, and the second defnitive hosts are many species of fsh (Kanev et al., 2002). Tey are known as yellow grubs due to their color and encyst in organs such as muscles, dermis and gills or in the body cavity (Olsen, 1974; Bullard and Overstreet, 2008). Research Article Abstract | Te study describes the intensity and histopathology of the Clinostomum complanatum infection in Garra rufa used in the health and beauty industries in foot spas for ichthyotherapy. In total of 25 examined fsh specimens 56% were infected with the metacercariae of C. complanatum. Te mean intensity of the infection was 27.14 cysts per host, varying between 1-75 cysts. Te parasites were determined encysted in the base of the fns, muscle, inner wall of the operculum, gill arches, lips, upper jaw, body cavity and palate, forming small 2-3 mm diameter white-yellowish nodules, easy to detect in macroscopical observation. Te highest prevalence of the metacercariae was in C. complanatum with 59.73% in gill tissue. Te parasites were found encapsulated by a thin connective tissue each containing a single parasite in muscle. Mercariae of C. complanatum were caused necrotic and fbrotic muscle tissues lesions in Garra rufa. Keywords | Clinostomum complanatum, Garra rufa, Histopathology, Prevalance, Intensity ÖZNUR ÖZIL*, ÖZNUR DILER, MEVLüT NAZIROğLU, AşKIN ATABAY Te Presence and Histopathology of Encysted Metacercaria of Clinostomum complanatum (Rudolphi, 1819) (Digenea:clinostomidae) in Garra rufa (Heckel, 1843) Editor | Muhammad Imran Rashid, Department of Parasitology, University of Veterinary and Animal Sciences, Lahore, Pakistan. Received | November 23, 2021; Accepted | August 22, 2022; Published | December 09, 2022 *Correspondence | Öznur Özil , Eğirdir Fisheries Faculty, Isparta Applied Sciences University, Isparta, Turkey; Email: oznurgormez@isparta.edu.tr Citation | Özil O, Diler O, Nazıroğlu M, Atabay A (2022). Te presence and histopathology of encysted metacercaria of clinostomum complanatum (rudolphi, 1819) (digenea:clinostomidae) in garra rufa (heckel, 1843). J. Adv. Parasitol. 9(1): 1-7. DOI | http://dx.doi.org/10.17582/journal.jap/2022/9.1.1.7 ISSN | 2311-4096 Copyright: 2022 by the authors. Licensee ResearchersLinks Ltd, England, UK. Tis article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY ) license (https://creativecommons. org/licenses/by/4.0/). Eğirdir Fisheries Faculty, Isparta Applied Sciences University, Isparta, Turkey.