Foodstall holders have been asked, for now, not to sell dishes containing two types of raw fish found to have traces of the Group B Streptococcus (GBS) bacteria.
The two types of fish are: Song fish, also known as Asian Bighead Carp; and Toman fish, also known as Snakehead fish.
The Ministry of Health (MOH) said it has found a link between the consumption of raw fish and GBS infection in a "limited number" of cases. But more cases will have to be studied before a definite conclusion is made, it added.
If the fish is well-cooked, GBS will not pose a problem, said a joint statement by MOH, the National Environment Agency (NEA) and the Agri-Food & Veterinary Authority of Singapore (AVA) last night.
Public hospitals have reported 238 cases of GBS infection in the first half of the year, up from an average of 150 cases in the last four years.
GBS is a common bacterium found in the gut and urinary tract of 15 to 30 per cent of adults without causing disease. However, it may occasionally cause infections of the skin, joints, heart and brain.
Those with chronic or multiple conditions are at a higher risk of getting GBS infections.
There has been no previous proven link between eating raw fish and serious GBS disease in humans, added the joint statement.
Last Monday, MOH said it was investigating the link between GBS and the consumption of raw fish with the NEA and the AVA. This was in response to WhatsApp messages warning of a bacteria outbreak from eating contaminated raw fish.
Yesterday, the authorities again urged vulnerable groups - young children, pregnant women, the elderly and people with chronic illnesses - to avoid eating raw food such as oysters or sashimi while investigations are ongoing.