Poor Ember, it does look like some of the photos I came across, and in the articles one of the common places for these to grow is along the lateral line at the base of the fins but also among other places on the body.
There is no treatment and eventually the fish's immune system will build a defense against it but it may take awhile. Keeping the fish in as less stress as possible, clean water conditions and it should go away on its own over time, from what I read, it appears not to be fatal..
btw, Ember looks an awful lot like my Midas boy...
