A highly sought after food fish, the Atlantic halibut is the largest flatfish in the world (2) (3). Flatfish exhibit a unique and distinctive anatomy that is adapted to their life on the sea bed; namely, they are flattened sideways and habitually lie on one side of their body, instead of being flattened from top to bottom like many others of the sea bed. As a result, both eyes tend to migrate to one side of the head during development. The Atlantic halibut lies on its left side and has both eyes positioned on its right, facing upwards (2). The fish is greenish-brown to dark brown or black on its upper surface and a dirty white on its lower surface (4) (5). Young fish are paler with more mottled colouration (3) (5).