By Zhang Shufang

An observant customer claims Wal- Mart is selling bowel-busting oilfish but marketing them as primo tasty sablefish.

Her mother suffered diarrhea after eating sablefish bought from the Wangjing Wal-Mart, according to Web user "Xiaoxian" posting Monday on a popular Wangjing community forum thread.

"I got suspicious when the fish became a fused mass during defrosting," Xiaoxian wrote.

"I watched a TV show that said people suffered diarrhea after consuming fish products labeled 'sablefish' which turned out to be oilfish.

"And then it occurred to me that what we bought was oilfish rather than sablefish."

Xiaoxian's post had attracted 2,066 viewers by 6 pm Wednesday. Some Web users posted saying they had suffered the same experience.

Eating oilfish, which contains indigestible wax ester, can cause diarrhea, said Liu Jing, a professor at the Institute of Oceanology in the Chinese Academy of Sciences.

"Wax ester is indigestible and thus accumulates in the rectum and may cause oily diarrhea and discomfort ranging from stomach cramps to rapid loose bowel movements," Li said.

They will check out the situation, a Wal-Mart Beijing office spokesman said.

"And if this is true," Jiang Wei said, "we will act."

Wangjing Wal-Mart sells two types of sablefish: the one Xiaoxian bought at 11.8 yuan ($1.7) per 500 grams and another at 119 yuan ($17.4) per 250 grams, according to the Beijing Morning Post.

A spokesman for Beijing Beifangyufu Food Company, supplier of Wal-Mart sablefish, told the paper that their fish costs at least 200 yuan ($29.3) per 500 grams and therefore any sablefish selling for 10 yuan ($1.5) had to be fake.

Japan and Italy prohibit the import of oilfish, according to the Center for Food Safety of Hong Kong. The Center issued its own guidelines on the identification and labeling of oilfish and sablefish in 2007.

No such regulations have been issued in the capital city, according to the Beijing Morning Post.