Help my fish have ich but my water has salt so why do they have it?

i bought 6 back neon tetras and 5 black skirt tetra and all the black neons and 2 of the black skirt have ich and i have salt in the tank so i dont know why they have it because the ich cant live in salt how can i cure it before it dies it has alittle bit so i can cure it in time i also have ich remover but if u have more cures and ideas share.