As fish stocks in the oceans continue to decline, aquaculture is supplying an increasing proportion of the seafood we consume.
Chefs and gourmets, of course, prefer fish caught in the wild and resist settling for a perceived inferior alternative.
But according to Lloyd Moskalik, managing director of Hong Kong-based supplier of aquaculture systems OceanEthix, farmed fish are no longer necessarily inferior.
The reef fish most favoured in Hong Kong and on the mainland, such as mouse grouper and coral trout, can now be farmed to a far higher standard than in the past, thanks to improved technology.
"Seafood farms need high-quality water, free of toxins, free of growth hormones, and free of heavy metals," says Moskalik.
"Fish farming methods tend to produce polluted water, leading to the use of antibiotics to treat the fish, so drugs are in the water, as well, and taste is compromised."
OceanEthix, he says, has solved this problem through what it calls the Atoll system - a 100 per cent water treatment recycling process in which fish waste is broken down into a fine powder naturally by bacteria.
"We put in water once - Bonaqua drinking water - and we import salt from Germany with no heavy metals. That [eight tonnes of] water is then recycled over and over again, and can remain in the system for five to seven years. You don't need to bring in any more water, or to pump any waste into the environment," he says.
Reef fish grown through this system, Moskalik says, consistently come out ahead in blind tastings against the same type of fish caught in the wild.
Patrick Zepho, former chef at Roka who is now a restaurant consultant and conducts classes in seafood preparation at the OceanEthix headquarters and aquaculture centre in Fo Tan, is also a believer.
"Fish in the system will actually have a stronger flavour because they are in clean water in a stress free environment," says Zepho, who regards fish from the Fo Tan tanks as of sashimi quality.
"A fish caught in the wild will always have a leaner taste to it, but the best way to have it is immediately. on the spot," he says. "By the time the fish gets to Hong Kong, if it doesn't come in live, it will already have rigor mortis, and that will change the texture and taste."
Zepho and OceanEthix are also partners in a venture called Exotix, which supplies fresh seafood from the facility to private customers.
Moskalik says his company's primary focus is on selling the technology, not the fish bred in the demonstration tanks. So, OceanEthix does not supply the restaurant trade.
Hyatt Regency Tsim Sha Tsui's executive chef, Michael Donlevy, has a clear preference for wild fish, but stresses that "they must be thoughtfully sourced, and the fisheries and their practices must be taken into account".
"The fish farm industry is still not able to provide high-end fish species to restaurants, but they will continue to develop, and hopefully we will see an increase in the aquaculture sectors in our supermarkets," he says.
Donlevy is unimpressed, so far, by farmed grouper and prawns, but comfortable with traditionally farmed shellfish such as oysters and mussels from cold waters northern Europe and southern Australasia. He is also prepared to consider farmed salmon, though mostly for reasons of cost.
"Eating wild salmon is a wonderful thing. It has a size, colour and flavour that are amazing, yet the price means many people may never get the chance to taste it. Among farmed salmon, the salmon from Tasmania is a clear winner on colour, texture, fat content, smell and taste," he says.
"Caviar, it was a taboo to think of farmed, yet now it is more accepted; otherwise, there would be very little available. I am pleased with the quality of the farmed caviar that is coming from China and Europe. There are many species and qualities to choose from."
Zepho adds: "I have been very surprised by the quality of the caviar coming from China. It's a very good product."
Because its aquaculture technology can function, as Moskalik puts it, "in the middle of the Gobi desert", OceanEthix is focusing on the mainland as a market.
As well as potentially reducing the depletion of marine fish stocks, the OceanEthix water recycling tanks offer the enticing prospect of truly fresh live seafood at locations far inland, which, on the mainland could have a powerful appeal.
Moskalik explains the company goes into joint venture partnerships with customers to manage the systems, putting staff onsite to ensure that their standards of aquaculture practice are uncompromised.
"We have three quite large projects that we're working on," he says. "The facility we have [in Fo Tan] is about 10 units. One that we're building in Dongguan [in Guangdong] is about 300 of these systems producing one to two tonnes of fish per day at full production. There's one we're doing in South Korea with about 1,000 modules. We're doing that with the Korean government. They are looking to move all their offshore aquaculture onshore because the water is getting so polluted. We have another small project in Shanghai, and another here at the airport."
Although the tanks in Fo Tan contain other seafood, Moskalik sees mouse grouper - which he says can be sold for up to US$100 per kilogram - as the fish highest in demand.
"The target of our technology is the high-value fish from US$40 to US$150 per kilogram," he says. "The demand for high-value live seafood in China is going through the roof, so there's a big demand for green technology. At the moment, they're using a lot of the more traditional aquaculture methods. They've set up sea cages in the ocean, and the water is highly polluted.
"This is where this sort of technology is coming to the fore. You need crystal clear water, or [mouse grouper] won't grow."
There is also potential for extended fish farming in Hong Kong, using repurposed factory space. Moskalik says he chose the 15th floor of an industrial building to demonstrate the viability of that option.
"The thing about the viability of fish farms is that in Hong Kong you don't have land, so how do you increase your production per square metre?" he says. "As you can see, you can do it vertically in a building."