Alternative treatment to malachite green of Saprolegnia sp. infection in Atlantic salmon

Saprolegnia infections were previously controlleld through the use of malachite green, an organic dye which has proven very efficient in killing all infectious stages of Saprolegnia sp. The use of malachite green has been banned in Norway and other parts of the world due to its potential toxicological effects. In Norway, the main disease problem caused by Saprolegnia infection in salmonid farming is seen in the hatcheries. Infections occur on eggs and the problem has increased dramatically since the ban on malachite green. Similarly, in countries like Scotland and Chile, were parr of salmon are kept in small net pens in freshwater lakes (lochs) an increased incidence of Saprolegnia infections in parr has occurred. The main objective of the project is to identify one or more suitable candidate compounds as commercial Saprolegnia sp. treatments. Initially, the project will aim at obtaining an epidemiological overview of the Saprolegnia sp. problem in Norwegian hatche ries and to charact erise the strains through classical mycological methods combined with molucular techniques. Based on results from studies revealing the effect against Saprolegnia and the relative fish toxicity of different compounds, the ultimate goal would be to obtain one safe and effective drug candidate for further development.