New treatment tackles costly parasitic disease for freshwater farmed and ornamental fish

Press release: 06 February 2020

A new treatment has been developed for Ichthyophthirius multifiliis, a parasite commonly found in freshwater fish which could save the ornamental and farmed fish industries billions of euro per year.

A compound was first identified by researchers from the EU-funded ParaFishControl project, which examines fish-parasite interactions in aquaculture. Its effectiveness in treating certain parasitic diseases led researchers to submit a patent for the compound.

The treatment was first tested on the I. multifiliis parasite, which causes white spot disease in a range of freshwater fish. The disease is highly damaging for both the ornamental and farmed fish industries due to its high mortality rate.

Ichthyophthirius multifiliis trophonts on a fin of common carp (Photo: C. Székely)

A new company, Sundew, has been founded to further develop and commercialise the compound. The Copenhagen-based SME will facilitate the development of large-scale production and purification of the product, which it has named BIOKOS.

The need for new treatments arose following the ban of malachite green, which was found to be carcinogenic and genotoxic. No other compound to date has been as effective for control of the infection.

Sundew owners are hopeful that BIOKOS will be in high demand in both the aquaculture and ornamental production markets. Aquaculture production alone is valued at over €5 billion per year in the EU.

This new treatment, and many other results originating from the past five years of research within ParaFishControl, will be presented at the project’s Final Conference “Innovative Strategies to Control Parasites in Aquaculture Farms” in Brussels on 11 March 2020. For further information and to register, please visit

To learn more about ParaFishControl, please visit the website at, or follow the project on Twitter @ParaFishControl.

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