This research aims to investigate the clinical symptoms of Myxobolus sp.-infected Koi carp (Cyprinus carpio) and to observe fish histopathology including histological alteration in the intestine, kidney, and liver organs. Descriptive method was employed in this research. The fish sample was obtained from Fish Farmer Group at Nglegok Village in Blitar City. The main observed parameters were the alteration of intestine, kidney, and liver of Koi infected with Myxobolus sp. parasite. The observation result of the histopathology of the parasite-infected fish indicated that necrosis and cyst occurred in the intestine. Necrosis also occurred in kidney, while hyaline degeneration occurred in tubule cells. Furthermore, necrosis and inflammation were also found in liver. It is obvious from the result that Myxobolus sp. infection resulted in the damage of Koi carp vital organs.
Keywords: Histopathology; Intestine; Kidney; Koi carp; Liver; Myxobolus sp..