Effect of different levels of injectable vitamin C on common carp, Cyprinus carpio survival challanged by different doses of theront of Ichthyophthirius multifilii

In this study, the effect of vitamin C injection on resistance promoting of common carp, Cyprinus carpio juveniles against doses of theront of Ichthyophthirius multifiliis was investigated. Average weight of fish was 36.5±14g. Required theronts were obtained according to Wahli method from infected ornamental fish. There was 24-hours interval between injection, and exposed to theronts. This experiment was carried out in 13 treatments include: 15 fish per each group, control (without injection vitamin C and challenge with theront), fishes were not injected and exposed to 3 levels of theronts in 250-5000-20000 per fish, 9 treatments with different levels of vitamin C, 200-500-1000 mg/kg BW, and challenged by different dosages of theronts, 250-5000-20000 per fish under in vitro condition (25-28ºC). The results showed positive effects of vitamin C injection, 500 and 1000 mg/Kg BW, on reduction of mortality rate, but injection of 200 mg/KgBW had no effect on mortality rate. Also, high mortality rate was observed in higher levels of theront concentrations. Mortality range was between 0% (control and 250 theronts) and 100% (without injection vitamin C and challenge with 5000 theronts, without injection vitamin C and injected by 200 mg/Kg BW and challenge with 20000 theronts).