The Pokfulam discovery is the first time the bug has emerged in a supermarket A ParknShop branch in Pokfulam was ordered to close its fish section yesterday after contagious cholera bacteria was found in a water sample taken from a fish tank. It is the second such case uncovered in Hong Kong within a week. All seafood being sold at the supermarket, located in Pokfulam's Chi Fu Fa Yuen housing complex, has been destroyed. It has not been decided when the section will reopen. The closure came after the Food and Environmental Hygiene Department confirmed the presence of the Ogawa cholera strain in a water sample collected from the fish tank on August 26. It marks the first time cholera bacteria have been found in a supermarket's fish tank in Hong Kong. The source of the contamination is not yet known. A week ago, bacteria of the same strain were found in the tanks of a small fish stall in the To Kwa Wan market. The stall remains closed and the source of the bacteria is unknown. Senior Environmental Hygiene Superintendent Cheung Sung-chi said routine tests had initially uncovered non-contagious cholera bacteria at five out of 20 ParknShop superstores visited by the department. 'It was not until further tests were conducted that we found the contagious bacteria in one of the samples and we decided to take action.' he said, adding the department would step up efforts to check fish tanks across the city. A spokeswoman for the supermarket chain said it had no intention of shutting down the fish stalls at all 50 outlets in Hong Kong, as precautionary testing had already been conducted. 'The fish tank water is a mix of chilled tap water with chemical salt,' said public relations manager Teresa Pang Sau-kwan. 'All fish tanks have also been fitted with a filtration system and ultraviolet lights. We have a regular water sampling and surveillance plan, but we have found no contamination so far.' Ms Pang said the seafood was sourced from both local and overseas suppliers. 'We also conduct regular visits to our suppliers to ensure that they meet our hygiene requirements.' Legislator Lo Wing-lok, who represents the medical sector, said he expected further cases to be uncovered in Hong Kong. 'It is pretty certain. The government must identify the suppliers of the seafood and the source of the water as quickly as possible.' A 19-year-old woman last month became Hong Kong's fifth reported cholera victim so far this year after being admitted to hospital on August 23 suffering from diarrhoea and mild abdominal pain. She was found to have digested cholera bacteria of the Ogawa strain. A health department spokeswoman said the woman had eaten a buffet of sashimi, sushi and assorted cooked seafood at a local restaurant the day before she fell sick.