User blog comment:ND999/Lore Hypothesis, Mt. Targon, Guardian Sea and Shadow Isles/@comment-25045713-20141209030128

Somehow I think Fizz's folks were not turned to zombies.

His family could be eaten by the Shark and the corpses were not found was a reference to in-game feature that when Fizz ult kills a yordle or enemy Fizz, the corpses will never show. Thats why the corpses are not present.

Now this shark, wanting all of them dead, went to Bilgewater to find the last of the kind,Fizz. Fizz, knowing he should protect the Bilgewater people, defeated the shark. Taming it and becoming the ult of Fizz.