I have done quite a bit of research on this ever since many years a go a friend of mine killed his dwarf SH by adding salt to cure some fin rot and killed his fish. The best think is to take it as they don’t like salt I have never had to use salt with my fish over the years and don’t like using it with them. Yes some are more salt tolerant but it’s just not worth the risk how much and witch ones. I will also let you into another fact, The New York State and environmentalists came up with this idea. The state environmental agency planners may try to flood a lake they have a SH problem with sea water, hoping to kill off the snakeheads and some other fish that also have a low tolerance for salt, but sparing other species. But yes some snakeheads can tolerate salinity but some of the small ones its death