Japanese researchers claim they have perfected a technique that will keep farmed fish and shellfish virus-free without the use of controversial anti-bacterial drugs or chemicals.

Microscopically small bubbles that carry ozone were successful in killing the Norovirus when circulated in seawater in experiments by scientists at the National Institute of Advanced Industrial Science and Technology in Tsukuba.

Norovirus is responsible for many cases of food poisoning in winter months, particularly from infected oysters. The success trials have led to team to start using the technique to suppress legionella bacteria and viruses that commonly effect livestock in fish farms.