The Food Business (Amendment) Regulation 2009 - which prohibits the use of seawater from any prohibited area for keeping live seafood - will come into effect on August 1.

The amended regulation provides that no people should extract, supply, deliver and use seawater from a prohibited area for keeping, in the course of food business, any live fish or shellfish that is intended for human consumption.

Offenders will be subject to a maximum penalty of $10,000 and three months' in prison.

The prohibited areas include Victoria Harbour, 14 typhoon shelters, areas along the shoreline of Hong Kong Island, including Ap Lei Chau, and along the western shoreline of the New Territories, including Tsing Yi.

The Food & Environmental Hygiene Department reminds the food trade to obtain seawater from reliable sources such as non-prohibited areas, reliable suppliers, and synthetic seawater from marine salt and tap water.

The trade should properly operate and maintain the filtration and disinfection system of fish tank water to keep the water at a satisfactory standard of E. coli less than 610 per 100ml and without pathogenic organisms.