Black Ghost Knife Fish Illness Advice

[Val Simo]

Photos attached...spot on side. Next pic shows the spot on side as well as streaky white marks behind that.

WHAT is it and how do I treat it?

 

[Colin_T]

Start a new thread and post pictures of the fish. Make sure the pictures clearly show the problem. Provide information about how long the tank has been set up for, what is in the tank. How often you do water changes and filter cleaning and how you do it. Tell us about what is in the tank and what has been added to the tank in the last few weeks.