The effect of fungicides on survival of the crayfish plague fungus, Aphanomyces astaci, Oomycetes, growing on fish scales.

Zoospores from the crayfish plague fungus Aphanomyces astaci could germinate and grow in vitro on scales of Salmo salar. The fungicidal activity of different compounds was tested against the fungus growing on fish scales as well as in lake water. Malachite green was the most effective fungicide, but scale mucus protected the fungus from this compound to some extent. For complete inhibition of spore germination in scale mucus 2 mg1-1 was required compared to 1 1 mg1-1 in lake water.