But Mr Prince Wong, managing director of Princes Association, which supplies fittings and fish for such businesses, said it was a fun activity. "Fish spas are meant to promote family bonding."

Still, experts said there are some things to watch out for. Dermatologist Patricia Yuen warned that cuts and wounds that come into contact with the water could become infected.

Those with skin problems, such as eczema, should also avoid soaking their skin for a prolonged period.

Operators of such spas contacted said they check that their customers do not have open wounds.

They added that they use filtration systems and ozonisers to keep the water clean and ultraviolet light to kill bacteria.

Such methods would usually kill most bacteria, confirmed Professor Sanjay Swarup from the National University of Singapore's Department of Biological Sciences.

The problem: Not all fish spas may be hygienic or use the right kind of fish. According to Mr Wong, about 50 per cent of shops do not use the Garra rufa, but lookalikes in the Garra family, or the Chin Chin (below), a biting fish that may cause micro-damage to the skin.

The Straits Times checked four shops and found one passing off the wider-bodied Chin Chin as the slender-body Garra rufa.

Still, complaints against fish spas here are rare.

This year, the Consumers Association of Singapore (Case) received one questioning the therapy's effectiveness in treating skin ailments, while The New Paper ran a story on two sisters who said they caught a fungal infection after visiting a fish spa.

Case executive director Seah Seng Choon advised consumers to exercise caution when using fish spas and to seek medical consultation for skin conditions.

ayiying@sph.com.sg

This story was first published in The Straits Times on Oct 29, 2008.

For more The Straits Times stories, click here.

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