The Monsterpedia description states: "A small shark that has been hunted to extinction in the wild. They only exist on the ranches of Monster Breeders."
Sharklett is an Event-only monster that was released in January 2012.
Appearing somewhere in the Divine & Demonic Lands for 1 week of each month, the Shark Hunter NPC will give the player a male and female lvl 5 Sharklett in exchange for a collection of items and monsters. These items and monsters differ each time the Shark Hunter returns.