Ectoparasitic Helminths During the Annual Cycle of the European Chub (Squalius cii, Richardson, 1857) in the Susurluk Basin, Türkiye: Their Infestation Levels, Identification, and Effect of Host Factors on Infection Levels

The ectoparasitic helminth in the European chub (Squalius cii, Richardson, 1857) was collected from the Susurluk basin from the Northwest region of Türkiye in the period from spring 2020 (April) to winter 2021 (February) once in every three months and also summarised. Only two species of Monogenea were found on the gills of the host and were identified as Dactylogyrus vistulae Prost, 1967 (Monogenea: Dactylogyridae) and Paradiplozoon homoion (Bychowsky & Nagibina, 1959) (Monogenea: Diplozoidae). D. vistulae was the most common and the highest number species. Other factors such as season, host length and sex were investigated to determine their effect on the infection values of ectoparasitic helminth infection, which were calculated from information collected from 79 host fishes. However, according to our current literature, there is no study in which S. cii is considered as a valid species and investigated in terms of ichtyohelminthological in Türkiye. This is the first ichtyohelminthological survey of S. cii in Türkiye and therefore new host and distribution records for all helminth species. Moreover, with such studies, scientists will have the opportunity to evaluate the infection success of parasite species belonging to this group, depending on the host, environmental conditions and enemies, and their infection success depending on the seasons and host factors. And data will be obtained about the complex life histories of the species belonging to this group and will contribute to the determination of the causes of death that will occur in both cultured and natural fish populations in the future.