The Efficacy of Copper Sulfate in Controlling Infection of Saprolegnia parasitica

Saprolegnia parasitica is a severe fish pathogen that causes important economic losses worldwide. Copper is an important additive in the aquaculture industry for control of algal growth, ectoparasites, and fungal disease. However, at present no data is available on the specific interaction of copper sulfate with oomycete. In our study, the efficacy of copper sulfate on the mycelium and zoospore of S. parasitica was assessed in vitro, and S. parasitica infection experiment was conducted to assess its performance in vivo. The results indicated that copper sulfate at >= 0.5 mg/L inhibited the growth of mycelium, no primary zoospores were released at >= 1.0 mg/L. Additionally, 0.5 mg/L copper sulfate could reduce the infection rate of S. parasitica in the grass carp, Ctenopharyngodon idellus. This study demonstrates the good efficacy of copper sulfate on the control of S. parasitica infection in grass carps, and suggests that copper sulfate could be used as a drug additive to control the S. parasitica infection in the aquaculture industry.