Ectoparasite infestation in silver carp (Hypophthalmichthys molitrix) of Hassanlu dam, West Azarbaijan Province, Iran

Silver carp fish (Hypophthalmichthys molitrix) rearing and production is a main source of protein in Hassanlu dam, West Azarbaijan Province, Iran.This study was aimed to determine prevalence and diversity of ectoparasites in silver carp of Hassanlu dam. A total number of 140 silver carp fish were randomly trapped during summer and fall 2015. Fish biometry recorded and gill was removed to examine for parasites infestation. The eye lens, fines and skin also removed and examined for ectoparasites.The findings revealed that ectoparasite infestation outbreak was in fish with 660.18±45.33 gr and 37.01±5.2 cm. Of all examined fish, 137(97.14%, monogenea), 119 (85%, protozoan),92(65.71%, digenean) and 14(10%, copepod) were respectively infested with Dactylogyrus spp., Trichodina sp., Diplostomum and Ergazilus sp. Four species of genus Dactylogyrus, i.e. D. aristicthys (97.14%); D. nobilis (49.28%); D. thaihoansis (34.28%) and D. skrjabini (7.85%) were identified. The eye lenses of fish were infested with metacercariae of Diplostomum spathaceum. The prevalence had significant association with weight and length of infested fish. Mixed infestation was found with two (12.86%), three (49.29%) and four (4.29%) parasites species. It was concluded that ectoparasite infestation was prevalent in gill and eye lenses of examined silver carp fish in Hassanlu dam and further studies recommended to evaluate infectivity and economical impacts on fish industry in the region.