Narelle Clegg, of the federal Agriculture Department's food safety branch, confirmed a rise in fish imports testing positive for banned antibiotics.
"The trend that we see with fish, and it's generally about antibiotics, is that they are very low levels of residues but they are there nonetheless," she said.
Chinese food failed the most tests, 13 per cent, followed by food from India, Italy, Japan, South Korea and France. The failed food results included 66 instances of Listeria monocytogenes, which can cause pregnant women to miscarry, and eight consignments with Vibrio cholerae bacteria, strains of which can cause cholera.
Dr John Turnidge, president of the Australian Society for Microbiology, said the results on Vietnamese fish imports were an obvious cause of concern because they can change the bacteria in people's systems and lead to resistance to antibiotics.
Australian National University professor of infectious diseases Peter Collignon said that while the fish had low levels of antibiotics, it was a problem. "If you are taking them into your intestine, they could have some effect on your own [bacteria] in your bowel and it can leave your own bacteria that used to be sensitive to antibiotics resistant," he said. "Perversely, continuous low levels of antibiotics can be worse than a one-off dose."
Professor Collignon criticised the federal department for its low levels of testing for dangerous chemicals. The department's figures show that in the last six months of 2011, it conducted just 209 tests for fluoroquinolones (types of antibiotic) and two for chloramphenicol, which in rare cases can trigger a fatal disease.
Professor Collignon said the department was not testing enough and the failure rate of the antibiotics tests - about four per cent - was too high.
Australia is now a net importer of seafood and heavily reliant on prawns and fish from countries such as China, Thailand and Vietnam. Fish and seafood imports grew 12 per cent from 2007-08 to 2010-11. Seafood imports from Vietnam increased $10 million in the last financial year to $162 million.
Norman Grant, executive chairman of the Seafood Importers Association of Australia, said the compliance rate of imported seafood was high.
"Occasionally, one of these things gets through the system, but the levels are so low as to be insignificant."
