Chinese importers target brown crab at Billingsgate
24 May 2012 Last updated at 00:14 BST
Billingsgate is London's oldest wholesale market and home to more than 50 merchants selling fish and seafood wholesale and direct to the public.
About 25,000 tonnes of fish are sold every year and there is increasing demand for luxury products including crabs destined for China.
The Fish Market: Inside Billingsgate is broadcast on Thursday 24 May 2012 at 2100 BST. Or watch afterwards on iPlayer.