Marcia Chase in Dalaran City wants you to bring her 5 Bloodtooth Frenzies.
The bloodtooth is a feisty little fish used in a recipe to cure infected wounds. We could use some of them, if you're up to it.
As the name suggests, they've a hunger for blood. The only way I know how to catch the little devils is by creating a blood pool and fishing in it.
Get yourself covered in blood - just slaughter a beast in the Borean Tundra - and then jump in the water. It'll wash right off and create the perfect fishing spot.