Spot checks of fish and prawns which have been farmed in Asia found that half contain bacteria which is resistant to antibiotics, according to animal rights organisation Wakker Dier.

The foundation had 43 samples of Asian fish and prawns tested for bacteria. One prawn sample was even found to have ESBL, an enzyme which prevents many antibiotics from working. It has previously been detected in meat but never before in fish, Wakker Dier said.

Campaign leader Hanneke van Ormondt says fish such as tilapia and pangasius are raised in giant tanks in Vietnam and Thailand and given huge amounts of antibiotics to combat illness. Antibiotics are also used to stimulate the fish to grow more quickly, she said.

Checks

If the fish is not properly cooked, the bacteria can also have an impact on human health by stopping antibiotics from working.

The Dutch food safety body NVWA said in 2009 there should be a proper system of checks on fish but this has not yet been developed, broadcaster Nos says.

A spokesman for the food retailers’ association CBL said this is now a priority. ‘We are going to increase our checks on fish farms and make it clear they should use fewer antibiotics,’ a spokesman told Nos.