how many of you have died to them fish I did a swan dive and thought yay that was good . needless to say I got owned by the fish. and you get a award for it as well so own up how many have done this for the award
Slaughter fish appear to be used to enforce boundaries on a map; in other words a clever way to keep you from trying to swim from, lets say a starter island, to the mainland. So most of us have this.
I also noticed it when travelling to an island for a quest. I was swimming and then stopped to go get a drink so i was inactive in the water and when i came back I was being attacked by slaughter fish :P