raised scales keep coming

for some reason only the platies in my tank seem to get raised scales. Eventually they die cause nothing I have on hand has helped. I don't even know what its called. BUt again no other fish get it what ever it is. SO my question is how do I cure them. It doesn't happen alot but I see one is starting to get that problem right now. I would like to know how to fix it so I can prevent any more loses. thanks!

Sorry to hear about the losses and problems.To better assist you can you please tell us the tank size,filtration,inhabitants,ph, ammonia, nitrite, and nitrate readings? If you have pictures that always helps too.

its just a plain old freshwater 55 gallon, regular carbon filters(one on each end of the tank). theres different kinds of cats, gourami, platies, sharks, that kinda stuff. other then this I can't say I have had any health problems - fish die here and there but I would say I have a healthy tank in general. I don;'t do any of the testing your asking for so I don't have any of those numbers. I have some kind of test kit on hand but haven't used it yet.don't even remember what its for :(

Would love to upload pics but not sure how

How to post pictures
https://usafishbox.forumotion.com/t3696-how-to-post-a-pic-picture-walkthrough