Re:On a More Serious Note (Score 2, Informative)

I made the same mistake on that quest. I killed one of the slaughter fish before taking the quest. However, i didnt know that was the cause of the glitch, i thought the quest from the start was buggy. I completed the quest by finding the fish without following the nav point (which fails to update). The fish appear one at a time after each kill. Took forever to do. Dispite some of the game's errors, the game is pretty amazing imo. Now u can go through what i went through haha jp