Iranian scientists have developed a filter to prevent fungal infections in farmed rainbow trout that could revolutionise industry practices.
The water filter is coated with silver nanoparticles that prevent fungal infections from forming in fish farmed indoors. The use of this filter could lead to replacing the practice of directly releasing nanoparticles into tanks, which has proved toxic to young rainbow trout.
The filter’s creation follows a study published in the Iranian Journal of Fisheries Sciences, which determined that the direct application of colloidal silver nanoparticles to tanks containing fish should be banned, especially for rainbow trout, whose largest world’s producer is Iran.
“We believe that the direct release of colloidal nanoparticles into the environment, especially in the aquaculture industry, must be prohibited,” Mohammad Reza Kalbassi, associate professor of aquaculture biotechnology at Tarbiat Modares University, Iran, and co-author of the study, SciDev.Net reports.
“However, indirect use in a filter or via other instruments after scientific consideration may improve [the aquaculture] industry in future,” the professor added.
He noted that using the new filter, made from nanosilver-coated minerals commonly used as commercial adsorbents, lengthened the rainbow trout’s survival rate.
“In contrast to the control group, where around 6 percent of fish had an infection caused by the fungus Saprolegnia, no infections were observed during the incubation period in the incubators containing nanosilver-coated filters,” he continued.
The filter has since been patented in Iran, he stated.
“The first challenge to the filter system is to contain the nanoparticles without loss as the water is passed through,” said Graeme Batley, chief research scientist at the catchment chemistry and ecotoxicology program at Australia’s Commonwealth Scientific and Industrial Research Organisation.
Batley pointed out that water passing through the filter could provoke a continuing release of low concentrations of ionic silver, which could result in a “build-up of ionic silver that could become toxic with time”.