This quest was marked obsolete by Blizzard and cannot be obtained or completed.
Take your Fragile Sprite Darter Egg to the Hinterlands and speak to Agnar Beastamer, but hurry, you only have 1 hour to find him before the hatchling within the egg dies.
A magnificent specimen, <name>. If this creature survives gestation, then it'll be a healthy pet indeed!
There is one last thing I would suggest doing if you plan on following through with this--head to Aerie Peak in the Hinterlands. Speak to a dwarf there named Agnar Beastamer, he's a master animal handler and should be able to guide you in the final steps of incubation.
But hurry, <name>, this egg is fragile and will not last long without proper care.