Unknown Ailment

[M1i1t1c1h1]

I need help identifying a potential ailment on one of my chromis. On one of its fins, there is a white line at the attachment point that wasn't there before. This white line is not in the skin (like a cut). It appears to be more of a growth on top of the skin. It doesn't look like any of the ailments I have tried to look up. I tried to get a picture of it but have been unsuccessful because this particular fish is afraid of me and hides whenever I go near the tank. The description is exactly as I said: A white line at the attachment point of the fin that appears to be some kind of growth on top of the skin. It is slightly jagged. The fish behavior is unchanged. It is still eating normally and schooling with my other 2 chromis. I did, however, notice that it is using that fin less than the other fin. Swimming appears to be normal but at a closer look when the fish is floating in one place, the fin with the white line is moving much less than the other side.
As I said, this description doesn't match any ailments on websites I have looked up. I am having trouble figuring out what it is. Any suggestions?

 

[Jay Hemdal Verified Community Expert]

Sorry, could be a variety of issues. Is it breathing faster than normal? Even with a clear photo, some diseases simply cannot be visually diagnosed. That said, sometimes a short video is easier to get than a photo.
Jay