The Impact of Leechiosis on Semi-Artificial Spawning Performance and Hematological Parameters of Silver Carp (Hypophthalmichthys Molitrix) Brooders and Common Carp (Cyprinus carpio) Fingerlings with A Reference to Its Stress Response and Treatment

Abstract

There was a decrease in artificial spawning performance of hatchery-reared cyprinid brooders in the spring of 2016 in an Egyptian hatchery. In this study, cyprinid brooders and fingerlings were clinically examined in situ, which showed that they were affected with leechiosis. Hemiclepsis marginata were identified as a causative agent of leechiosis. The prevalence of leechiosis was highest in silver carp (Hypophthalmichthys molitrix) brooders and common carp (Cyprinus carpio) fingerlings. The infested brooders and fingerlings showed red to white marks, severe hemorrhages, and dark contracted worms on their skin. The impact of leechiosis on semi-artificial spawning performance and hematological parameters of H. molitrix brooders was evaluated by determining the eggs weight, fertility, hatching percentage and the complete blood picture. Leechiosis had a significant impact on eggs weight, fertility, and hatching percentage. Microcytic hypochromic anemia, leukocytosis, lymphopenia, and heterophilia were recorded in the infested brooders. Regarding the association between leechiosis and stress response, the total antioxidant enzymes were found to be significantly decreased, whereas malondialdehyde levels were increased in the infested brooders compared with those in control samples. Under the experimental condition, leechiosis could be controlled among C. carpio fingerlings using trichlorfon, after which normal hematological parameters were recorded for the treated C. carpio fingerlings. Regarding the field conditions, trichlorfon could successfully control leechiosis in H. molitrix brooders and C. carpio fingerlings.