It has been found that is farmed fish are fed by-products rendered from cows, they could transmit Creutzfeldt Jakob disease (otherwise known as the 'mad cow disease').
Questioning the safety of eating farmed fish, Dr. Robert P. Friedland, a neurologist at University of Louisville, has urged government regulators to ban feeding cow meat or bone meal to fish until the safety of this common practice can be confirmed.
"We have not proven that it's possible for fish to transmit the disease to humans. Still, we believe that out of reasonable caution for public health, the practice of feeding rendered cows to fish should be prohibited. Fish do very well in the seas without eating cows," said Friedland.
Creutzfeldt Jakob disease is an untreatable, universally fatal disease that can be contracted by eating parts of an animal infected with bovine spongiform encephalopathy (BSE or mad cow disease).
The risk of transmission of BSE to humans who eat farmed fish would appear to be low because of perceived barriers between species.
But the researchers have said that it is possible for a disease to be spread by eating a carrier that is not infected itself.
It is also possible that eating diseased cow parts could cause fish to experience a pathological change that allows the infection to be passed between the two species.
"The fact that no cases of Creutzfeldt Jakob disease have been linked to eating farmed fish does not assure that feeding rendered cow parts to fish is safe. The incubation period of these diseases may last for decades, which makes the association between feeding practices and infection difficult. Enhanced safeguards need to be put in place to protect the public," said Friedland.
The study has been published in the Journal of Alzheimer's Disease.