They will be sold for HK$60 to HK$70 each, about double the price for non-organic fish of the same type on the market.

Each fish will be labelled with a green sticker with a tick, the word 'organic' and the centre's name to identify them as certified organic.

From next month, one of the farms will sell fish at its own retail outlets. Wong expects that more fish will soon be available in selective supermarkets.

'Organic fish are safer to eat as they are chemical-free,' he said. 'Eating them also benefits the environment.'

He said the two farms had to comply with many international standards to earn their organic certification.

Apart from providing organic feed and unpolluted water, the farms had to ensure they had adequate space for the fish.

'The fish need enough room to swim,' Wong said. 'If it gets too crowded, they can be injured.'

The fish were raised and killed humanely, Wong said.

He explained that methods commonly used in wet markets were acceptable, such as knocking fish unconscious with a hard blow before gutting them. But drugging fish was prohibited as this would contaminate them.

Wong is confident that organic fish farming has a future in Hong Kong. 'We are now at the kick-off stage but hope more fish farmers will join the project,' he said.

The Organic Resources Centre was co-operating with the two farms, with technological support from the Agriculture, Fisheries and Conservation Department.

When the fishing operation is more well established, the farms will breed more expensive species to raise profit margins and make it more attractive to fish farmers.

'Farming organic fish should be more profitable than breeding non-organic fish,' Wong said.

For now, only freshwater fish can be cultivated organically in Hong Kong as there are no isolated bays suitable for organic mariculture. 'We can't raise organic fish with non-organic types as they will be contaminated by chemicals and pollutants,' Wong said.

Organic fish provided a safer and more environmentally friendly choice for consumers, Wong said, as organic fish farms strive to minimise water pollution.

Their carbon footprint was much lower as they did not use fertilisers and pesticides, which were petroleum by-products.

More than 70 per cent of the farms' fish feed is organic, meaning it has been produced with no chemical fertilisers, additives and hormones.

The fish are fed mainly residue from organically raised soya bean and fishmeal.

Water quality at the farms is also strictly controlled. The pond water and mud must be free of pollution, and any waste water from the operation is treated before it is discharged.

Healthy profits

Organically raised fish fetch higher prices than traditionally raised stock

The number of farms involved in Hong Kong's pioneering organic fish-raising project in Yuen Long: 2