BEIJING • In supermarkets across the Chinese capital, shoppers have been staring, baffled by empty fish tanks and asking: Where have all the fish gone?

Carp and other freshwater fish usually sold alive have disappeared from sale in recent days, leaving behind vacant tanks and shifting, contradictory explanations from officials and supermarket managers.

The missing fish and murky information have become a big deal for city residents bruised by dozens of food safety scares.

"Yes, I love eating freshwater fish, like catfish and carp," said 73- year-old retiree Zhu Lanrong at a supermarket in south-east Beijing.

"If there was nothing wrong with the fish, they wouldn't have cleared them out. Something is wrong, and in fact it's not only about fish, but all kinds of food."

The Beijing Food and Drug Administration has denied that there was any outbreak of pollution that tainted fish. It said that any decision to halt sales was "normal commercial behaviour" by retailers voluntarily adjusting to changing consumer demand over many months.

In a country where contaminated food is a chronic worry, removing the fish so swiftly from sale has seemed highly suspicious to shoppers. "I don't know whether it is because of water pollution or to evade inspection," said 64-year-old retired worker Yu Huaying, who had gone to her local supermarket to buy carp.

"Either way, something is wrong with the freshwater fish."

The front page of The Beijing News on Thursday was dominated by a picture of the empty tanks at a supermarket.

"When the live fish mysteriously disappear from some supermarkets, when there's a plethora of public explanations, when rumours and doubts abound, in the end it all comes down to having no sense of psychological security," the paper said in a commentary.

Not all supermarkets have removed their live freshwater fish. But in many other stores in Beijing, freshwater fish are gone with no explanation.

Caixin, a respected business magazine, citing an anonymous source, reported that supermarkets had removed fish after word leaked that national inspectors would begin a wide-ranging check for banned chemicals and additives in foods.

Southern Weekend, a weekly newspaper published in Guangdong province, said some retailers appeared fearful of heavy fines for using excessive amounts of antibiotics and other additives in water to keep fish alive and free of disease.

The Beijing Food and Drug Administration said on Thursday that rumours of an outbreak of pollution that left lingering toxins in fish were groundless, and there had been no directive to retailers to stop selling live freshwater fish.

Calls to Carrefour, Wumart, Jingkelong and other supermarket chains in Beijing went unanswered or brought claims of uncertainty about the reports. Some managers and sales assistants have told Chinese newspapers that they were simply changing suppliers of live freshwater fish, or were shifting to sale of frozen fish.

There have been no health reports that would suggest a spike in poisoning from fish. And at a wholesale market for fish and aquatic products in Dahongmen, southern Beijing, business was reportedly normal.

"I don't know why some supermarkets aren't selling live fish," said fish wholesaler Huang Minsheng.

"Consumers are full of doubts," the Huangshan Daily, a newspaper in north-west China, said in an editorial on Thursday. "But none of the supermarkets has offered a reasonable explanation. Without a clear explanation, there'll be no easing of public anxiety."

NYTIMES