I had game with over 100hrs into i would swim through water all the time countless amounts of times never seen a single slaughter fish downloaded the patch and started new game firt river i went in i got swarmed by 4 slaughterfish i kno this is unimportant but did patch add evil fish???

No I've seen the pre-patch.

They may have added more so we die another way during massive lag to piss us off but who knows?

no there's plenty of slaughterfish pre-patch. Maybe they fixed it so the game would randomly generate more of them in certain areas where there werent as many before?