Seafood From Asia Raised on Pig Waste, Says News Report Report says fish from East Asia may carry salmonella and been fed pig waste.

Oct. 17, 2012 -- "Would you like flies with that?" Seafood raised on pig feces and crawling with flies is being sold to U.S. consumers, according to a new report.

The November issue of Bloomberg Markets magazine, in a piece on food poisoning and safety, says that it is common practice in some parts of Asia to feed fish pig waste. It describes, for example, the sanitary conditions at a fish factory on the southern coast of Vietnam. "Flies," it says, "crawl over baskets of processed shrimp."

The shrimp at some plants are packed in ice. That's good. What's bad: it's ice made from water often found to be contaminated with bacteria and unfit for human consumption, say Bloomberg's reporters in Hanoi.

Vietnam ships 100 million pounds of shrimp a year to the U.S., about 8 percent of the shrimp sold in America.

Reuters says the U.S. Food and Drug Administration in June recommended removal from the U.S. market of South Korean shellfish, including clams and mussels, because, said the agency, the fish might have been exposed to human fecal waste or otherwise contaminated. At least 4 U.S. consumers have become ill after eating South Korean seafood, said the FDA.

Outside Hong Kong, at a tilapia farm, fish are fed a diet that includes pig and geese feces. That practice, Michael Doyle tells Bloomberg Markets, is unsafe for U.S. consumers, because the manure may be contaminated with salmonella. Doyle is director of the Center for Food Safety at the University of Georgia. Fish farmers, he says, use fecal matter as a cheaper alternative to commercial fish food.

The FDA inspects food shipments to the United States, including seafood shipments, but the agency's resources are limited, says Bloomberg's report. It is able to inspect fewer than 3 percent of shipments. Of that, reports Bloomberg, much is sent back. The FDA has rejected 1,380 shipments of Vietnamese seafood since 2007, finding filth and salmonella.

Kevin Fitzsimmons, a professor and research scientist at the University of Arizona College of Agriculture and Life Sciences, tells ABC News he has read the Bloomberg article and finds it "a little misleading. I do a lot of work in Asia and am headed there now for a conference on tilapia. They [Bloomberg] are cherry-picking a few items to make things sound as bad as possible." Fitzsimmons is an officer of the American Tilapia Association and an expert on seafood production in Asia.

For starters, he says, seafood shipments from Asia to the U.S. number in the "hundreds of thousands, if not millions," so the fact that 1,380 from Vietnam have been returned since 2007 is relatively insignificant.

Second, he says, the practice in Asia of putting hog feces into fish ponds dates back "thousands of years," and is not as repellent as it at first might sound. Why? "Because the fish are not eating the feces. The feces are added to the water to produce an algae bloom," he says, which in turn produces a form of plankton that the fish then eat.