From Creatures Wikia
The genome of the Zwergbunt Grendels is known as the "Nice Grendel" genome.
They are more placid than standard grendels, leaving norns and ettins alone for the most part, while at the same time remaining true to the core characteristics of their larger relatives.
In addition, females will not age after laying an egg and both genders have a slightly longer lifespan than normal grendels.
They also have more Pigment and Pigment Bleed genes than standard grendels, making color editing through genetics a far less ardous task.
Zwergbunt Grendels can be obtained from Creatures Unlimited.