Feed them budweiser and then you can safely pass.
jokes a side: No it is not a bug. The slaughterfish are not there to amuse you, they are there to stop you, whatever you do. The reason is that you simply can't swim to stormhaven. The place you are trying to reach is actually a different zone and so it means you need to be reloaded into it. Behind those slaughterfish is not really stormhaven, but an endless void.
https://youtu.be/P-EDkr_GlVUjokes a side: No it is not a bug. The slaughterfish are not there to amuse you, they are there to stop you, whatever you do. The reason is that you simply can't swim to stormhaven. The place you are trying to reach is actually a different zone and so it means you need to be reloaded into it. Behind those slaughterfish is not really stormhaven, but an endless void.
This. Slaughterfish are a replacement for invisible walls when you try to swim where you shouldnt'.
Though in fact I'd prefer to be mauled by a giant sea creature than slowly eaten alive by tiny carnivorous fish...