Abstract
he antimycotic activities of thymoquinone against some species of Saprolegnia pathogenic to fish as well as its toxic effect on selected farm fishes were investigated. Two Saprolegnia species pathogenic to fish, S. parasitica NJM 8604 and S. salmonis NJM 9851, were used. The minimum inhibitory concentrations (MICs) of thymoquinone against Saprolegnia parasitica and S. salmonis were 150 and 125 μg/ml, respectively, while the fungicidal effects on both strains were seen at 160 μg/ml. Tested zoospores of both Saprolegnia strains could not germinate after being exposed to 4 μg/ml of thymoquinone for 30 min. Thymoquinone was toxic to salmonids but less toxic to cyprinids.
