Blue Tiger camouflage is achieved by obtaining 75 headshots with a specific weapon, or 50 headshots for the W1200 and M1014. It has a pattern much like Woodland and Desert, except it has a black and blue shade added to it.
While the Red Tiger camouflage requires more headshots to unlock than Blue Tiger, some players prefer Blue Tiger to Red Tiger, because it is more noticeable and striking in all lighting (Red Tiger is almost invisible on some weapons in low light maps such as Wet Work). In some instances, Blue Tiger can actually provide some camouflage function on maps like Wet Work and Vacant, which feature an abundance of blue hues.
In Call of Duty: Modern Warfare 2, Blue Tiger returns as a camouflage option, only instead of being a blue and black pattern, it is now two shades of blue, one darker and one lighter with a similar pattern. However, it is hard to see on some weapons (like the UMP45) because of the limited camouflage on the gun. It is unlocked after 75 headshots in multiplayer.
Like Red Tiger Camouflage, the Call of Duty: Modern Warfare 2 version is more pronounced than the version from its predecessor.