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Launch of – Have you seen a fluffy fish?

Our PhD student Emily Matthews is collecting samples of the fungal-like organism Saprolegnia. There are several different species of Saprolegnia, but S. parasitica is the main species that infects fish causing the disease saprolegniasis. Typical signs of infection include patches of white cotton-like fluff on the skin, fins and gills of infected fish. This fluffy “fungus” destroys the surface tissues of the fish before penetrating into the muscle layers and blood vessels. As the infection progresses, the regulation of water and mineral salts in the fish’s blood (a process known as osmoregulation) becomes impaired, eventually resulting in death.

Aquaculture is the world’s fastest growing food industry. S. parasitica infections have a huge impact on the economic prosperity of this sector, with saprolegniasis-induced deaths reported in 1 in 10 farm-raised salmon. The Scottish salmon farming industry alone suffers an annual £5 million loss due to this fluffy fiend! Declines in natural wild fish stocks, particularly salmonids, have also been associated with S. parasitica. These infections are placing increasing pressure on wild fish populations and greatly impacting associated fisheries.


A major aim of Emily’s PhD is to develop a method to identify and distinguish between different strains of S. parasitica. This will allow us to monitor the movement of S. parasitica strains in the environment and identify infection pathways between farmed and wild fish stocks and vice versa.

In order to achieve this, Emily needs to collect a large number of Saprolegnia samples from around the UK. Emily is working closely with the Environment Agency to source these samples, but also needs help from members of the public! To find out how you can get involved, please take a look at our new website,

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