From Creatures Wikia
The Lungfish Grendels are a blue tinted amphibious breed created by Empyreal which function normally under water, and after 5 minutes on land go into a state of hibernation, but when put under water wake up. They breed very quickly to make up for the fact that when left alone, they may go onto land and hibernate until death by old age. Norngarden 4 is recomended. The temporary download location of the Lungfish Grendels is here.
The Ettin version of this breed are the Lungfish Ettins.