In recent years, AGD has become a serious disease among farmed salmon at sea. Researchers are now developing a new treatment method that will be gentler for both fish and the environment compared to existing forms.
Currently, farmed salmon affected by AGD is treated with fresh water or bathed in hydrogen peroxide. Researchers are now evaluating whether peracetic acid can be a more sustainable alternative.
Peracetic acid is an oxidizing acid that is widely used as a disinfectant in recirculating aquaculture systems used for rainbow trout. It is used because it disinfects without damaging the beneficial bacteria in the biofilter.
The objective of the initial trials is mainly to investigate whether peracetic acid is safe to use in the treatment of salmon. Researchers from Nofima, the Norwegian Veterinary Institute and the Technical University of Denmark have tested several doses in fish and separately on the amoeba in three trials.
Not harmful to salmon
The preliminary conclusion of the scientists is that peracetic acid is not harmful to salmon, that it has an effect on the amoeba that causes the disease and that there is a low environmental risk when used in this regard.
“When salmon are exposed to peracetic acid, they react as if there is something new in the water, but the behaviour and physiological responses indicate that it is more about adapting to change than affecting the health and welfare of the fish. It also did not affect the appetite,” said Carlo C Lazado, fish health researcher at Nofima and project leader.
Peracetic acid has an effect on the amoeba by reducing its viability in vitro. Peracetic acid is considered a more sustainable alternative to hydrogen peroxide because it appears to be effective in smaller doses and breaks down more rapidly into components that are more neutral.
The researchers hope to further develop the method of treatment by testing peracetic acid in salmon infected with AGD. They will then get answers on what concentrations are most effective on the amoeba, while not negatively affecting the health of the salmon.