In Hong Kong, where factory space is stacked in skyscrapers, the 15th floor of an industrial block houses vast tanks in which thousands of rare fish swim under the eerie, purple glow of UV lights.

Normally found thousands of miles away on the reefs of the tropics, the coral grouper are being bred on land in one of the world's most densely populated metropolises to feed a local population that consumes 3.6 times the global average in seafood.

Sold live, fish like leopard coral grouper are highly valued in China, where ostentatious dining calls for expensive and attractive centerpieces for celebratory or business banquets - last week during the Lunar new Year a single fish could cost around $130.

But even the tons of fish swimming in the tanks of OceanEthix incongruous high rise facility can't sate a growing market for live reef fish in Hong Kong and mainland China that is worth around $1 billion each year.

Read Small fish, big business: Asia's billion dollar live reef fish trade

Previously – Growing shrimp in the desert and The shrimp are coming from inside the house