Investigation of external parasites in fish in Mosul city

Two hundred samples of five fish species were taken from local marketplaces in Mosul from Aug. 2023 – Feb. 2024. Results revealed that fish were infected with four types of external protozoans, Ichthyophthirius sp., Trichodina spp., Piscinoodinium sp., as well as Chilodonella spp. The highest infestation rate was recorded in Trichodina was 19.5%, then Chilodonella, Ichthyophthirius were 7.5%, 6.5%, respectively, while the lowest infestation rate was recorded in Piscinoodinium was 3%. No significant differences were recorded during the months of the study. The location of the external protozoa varied in the skin, gills and fins. The ectoparasite Trichodina was isolated from different places in fish skin, gills, in addition to fins. Ichthyophthirus was found on fins and in gills, whereas Chilodonella and Piscinoodinium were found on the skin and in gills of fish. This study also detected for the first time the presence of the ectoparasite Piscinoodinium pillulare, which was in a round shape, golden to brown and of different sizes.