Correct, you don’t want to damage a fish for pictures, treatments, etc. sometimes it is safer to just do nothing and observe.I do not think i can manage a better picture unless the fish is restrained. It might do more damage then its worth.
That doesn’t look like Uronema to me and I’ve never seen that disease on this species. It could be a secondary bacterial infection from an injury.
I would just observe for now.
Jay