To the hordes of lost Oblivionites

Welcome to all the people who are coming here via googling for "slaughterfish". Hah. You won't find much of use here.

Well, all right. One hint: I've had more luck finding slaughterfish in the sewers than I have in the main lake. Also there seem to be more of them around the higher level you are. So try waiting until you're level three or four before taking that mission.

Update: actually I'm wrong about all of that. For this mission you need one specific slaughterfish. And you will only find it in the lake, and only by using the "detect life" spell.