This should help clarify exactly what goes on in the background.
If buying through a site such as Aquabid, you buy the fish you want and pay the seller the price of the fish + $4. This $4 that everyone pays gets pooled together to pay for the cost of flying the fish out to the UK. Your seller will hold onto the fish until the shipment is due. Once you have finished your 'shopping', you can then email me with the total number of fish. I will let you know how much it works out at.
All sellers with fish destined for the UK send their fish to my exporter the day the shipment is due to fly out. My exporter packs all the fish together, books it into cargo and sends me the paperwork. I forward the paperwork to my customs clearance agent, who forward it on to customs, so they are ready to let the fish through.
The next day -
To import live fish and shellfish I must be authorised by the Fish Health Inspectorate (FHI). Authorisations explain the minimum legal standards which are required of the importers. This includes; record keeping, certification and biosecurity measure plans.
All wildlife imported to the UK must be declared to customs and to CEFAS. This is simply to keep track of diseases. All animals coming into the country must do so through a ‘port’ adapted to receive such cargo. There are only 3 airports in the UK that are designated entry points for live animals.
I strongly recommend you read this article: http://www.practicalfishkeeping.co.uk/content.php?sid=847
It will tell you more about the reasons behind the licence requirements and why you don’t want to try receiving fish illegally.
Once I have the fish, I pack them into their individual boxes and send them out the next day.