Flashlight fish without lights?

[Still_human]

I’ve seen it mentioned, but nothing about why, or what to do! My little guy seems as healthy as ever, but his lights seem to be almost out. They REFLECT light pretty well, which I can tell cause he leaves them uncovered a lot now, at least around feeding time, but Ive recently noticed how dim they’ve been getting, and now possibly out. It’s in my QT tank still, and I’ve never introduced any medications since the tank was set up for him, but I’m sure there’s residual copper in the rocks and everything. I didn’t think of copper as a big anti-bacterial agent! Is it? His lights didn’t start diminishing for many weeks.