The flowerhorn kok or nuchal hump is the crowning glory of this fish. Often associated with luck it is actually a storage area of fat. The more fat stored in the nuchal hump the bigger it gets. Below are pictures of fat that is stored in the nuchal hump.
Types of kok.
1. Hard kok
Reminiscent of old school flowerhorns. Hard koks are usually just a small protrusion on the forehead of the male flowerhorn. As the name implies if you touch the head part the area feels hard and flat this is due to minimal amount of fat deposited in the nuchal hump. They are usually not that attractive unless the fish has wonderful pearl and color patterns. Flowerhorns with this type of kok can be entered in a flowerhorn show under the free head category.
A combination of hard and water kok.These koks don't grow to be enormous but may grow to a certain size which may be harmonious to the general appearance of the flowerhorn. These koks would feel soft on light pressing but the hard kok would be felt underneath the soft water kok when you press the kok area a little harder. Also when you shine a light behind the kok area the translucent part of the water kok would be evident.
The most sought after kok is the water kok. These kok has the potential of growing to enormous size. It feels soft all throughout and would appear translucent when light is shone through it.
1. Egg shaped or kidney shaped