But inside Bluu Seafood, past the slick open-plan coffee and cake bar, the rooms are dominated by gleaming white tiles, people bustling about in lab coats, rows of broad-bottomed beakers and pieces of equipment more at home in a science-fiction thriller. A 50-litre tank (a bioreactor) is filled with what looks like a cherry-coloured energy drink. The liquid, known as “growth medium”, is rich with sugars, minerals, amino acids and proteins designed to give the fish cells that are added to it the boost they need to multiply by the million.