Consuming raw freshwater fish (Chinese Yu Sang) can be hazardous to health. Raw freshwater fish including grass carp, bighead carp or snakehead may carry parasites such as Chinese liver fluke, which can cause obstruction, inflammation and cancer of the biliary ducts in the liver. Chinese liver fluke contributes to the majority of local human cases of enteric parasites.

In addition to parasites, eating raw or undercooked freshwater fish can lead to foodborne infections. In the past, there were outbreaks of Group B streptococcus (GBS) infections in Singapore which were associated with raw freshwater fish consumption. GBS can cause infections in different parts of the body including the bloodstream, lungs, bones and joints. People, especially the elderly and people with weakened immunity (e.g. people with chronic diseases), may also contract GBS by exposure to seawater through an existing open wound or a puncture wound when handling raw aquatic products.

In order to protect public health, raw freshwater fish (Chinese Yu Sang) is a prohibited food under the Food Business Regulation (Cap 132X) in Hong Kong. Consumers are advised not to eat raw or undercooked freshwater fish while dining locally or travelling and eat freshwater fish only if it is adequately cooked, especially when having hot pot or congee.

To prevent foodborne diseases, the public should also pay attention to personal, food and environmental hygiene: