Freeing fish farms from infection

A cheap and environmentally friendly system for cleaning polluted water has been developed to keep fish farms free from infections.

The research is reported in the latest edition of the Royal Society of Chemistry's Journal of Environmental Monitoring.

A report published by the United Nations Food and Agriculture Organisation shows that nearly half the fish consumed the world are farmed rather than caught in the wild.

Dr Michela Magaraggia and a team from the University of Padova, Italy, developed the technique to prevent fungal infections in trout farms.

By adding porphyrin containing compounds to the water and shining light on them, oxygen species are created which attack their immediate surroundings. 

The disease causing fungus Saprolegnia is killed by these oxygen species, allowing infected trout to recover and preventing new infections occurring.

Dr Magaraggia said: "Concentrated fish populations, such as those found in fish farms, provide ideal conditions for fungal infections. Infections in fish eggs represent a heavy financial loss worldwide."

The new technique could potentially remove a wide range of disease causing micro-organisms.

Dr Gianluca Li Puma, of the University of Nottingham, said: "This will eliminate the current practice of using carcinogenic chemicals such as formaldehyde as the main disinfecting agent."

Dr Magaraggia added that the porphyrins used in the technique would not accumulate in the environment because they are broken down by light.

She said: "The technique could also answer some wider issues for sanitation. It could be potentially expanded to the treatment of irrigation or drinking water- a major problem in developing countries for the prevention and limitation of diseases."

with thanks to Michele Zgraggen for the original article