Snails / Ghost ,Ivory & golden

Question
I have a problem with my golden and ghost snails that seems to have started with adding MELAFIX for finn rot with one of my tetras.The spirals on the shells get white specs / pits & the shell completly dissolves at the spiral tip in just several days & the snails eventually expire.The fish are doing great but even when several months go by and I replace them the same thing happens.

Answer
It sounds to me there is still some of the Melafix in the aquarium causing the problem with your snails, you may want to wait much longer and try with an inexpensive snail to see if the Melafix has worked its way out of your system. Wish I could be of more assistance.