Supersized genetically modified salmon grown fast and fat and after years of wrangling, are ready for market – but is the market ready for them? And why is the firm hidden away in Panama?It is hard to think of a more unlikely setting for genetic experimentation or for raising salmon: a rundown shed at a secretive location in the Panamanian rainforest miles inland and 1,500m above sea level.But the facility, which is owned by an American company AquaBounty Technologies, stands on the verge of delivering the first genetically modified food animal – a fast-growing salmon – to supermarkets and dinner tables.The US government this week enters the final stages of its deliberations on whether to allow commercial production of the GM fish, with a public consultation on the issue ending on Friday.