I cannot be for sure, being they were so small I did not notice until recently.So if salt will not hurt them maybe I should go ahead and try it, or is there something else I should try? If they were born without will they survive?
I think I should have been more specific.
Are you saying they were born with dorsal fins, and they have rotted away? Or are you saying they were born without dorsal fins?
If they were born without, I doubt any treatment will help.
If it's a fungus eating the fins away, yes salt.
I must admit, I don't use aquarium salt, I find it unnecessarily expensive, I just buy a 20 lb bag of rock, or water softener salt from the hardware store and use that.
NaCl is NaCl, unless it has an additive.