Isolation and identification of Capillaria sp. in ornamental green terror (Andinoacara rivulatus Günther, 1860) farmed in Iran

Green terror (Andinoacara rivulatus) is one of the most popular freshwater ornamental fish of the Cichlidae, which is commonly bred and cultivated in Iran. The aim of this study was to investigate the main cause of green terror mass losses in an ornamental fish breeding center in Nazarabad, Alborz province. Following chronic and continuous losses of mature green terrors with clinical signs including white feces hanging from the anus, the fish were sampled between June 2021 and July 2021. The fish were packed in water-filled polyethylene bags and transported to the Ornamental Fish Clinic, Faculty of Veterinary Medicine, University of Tehran. In macroscopic examinations, cachexia and paleness of the fish were evident. In order to investigate ectoparasitic infestations, wet smears were prepared from skin and gills, and examined under a light microscope. However, no parasitic infection was observed. In addition, the fish were euthanised, necropsied, and internal organs such as the intestine were examined. Microscopic examination of the intestine showed a heavy infection with mature Capillaria sp. and the barrel-shaped eggs. In the present study, the severity of Capillaria infection was very high and determined to be the main cause of losses. In order to treat the other fish in the population, levamisole was administered for 48 h every 7 days for 28 days. After re-examination, fish losses completely stopped, and no infection was observed after 28 days.