Please help ID white spot on a JD. PICs

[bennylax3]

My Jack Dempsey has a white hole or indentation on his side. Could somebody help identify and offer some treatment solutions?

He currently has been moved to a smaller quarantine tank where I have raised the temperature and added some aquarium salt.

 

[peifc]

I have had the same problem on some of my fish. Then it disappeared after some good water change for about 2 weeks.