Diablo Wiki

Moontooth Dreadshark, The Shadowswimmer is a unique Sand Shark that can be found in the Sewers of Caldeum in Diablo III. It hides in a pile of rubble that breaks when you approach it, in one of the dead ends of the sewers.

It has Electrified and Fast affixes.

This is the only monster in the game that can drop The Murlocket.