The halibut is the largest flat fish, averaging 11–13.5 kilograms (24–30 lb), but catch as large as 333 kilograms (734 lb) have been reported; the largest recently recorded[2] was 211 kilograms (470 lb) and 2.5 metres (8.2 ft) long.[3][4] They are gray-black on the top side with an off-white underbelly. At birth they have an eye on each side of the head, and swim like a salmon. After about 6 months one eye migrates to the other side, making them look more like flounder. At the same time the stationary-eyed side darkens to match the top side, while the other side remains white. This color scheme disguises halibut from above (blending with the ocean floor) and from below (blending into the light from the sky) and is known as countershading.