Definately keep an eye on the fish but I wouldn't be in a hurry to treat with meds. I would suggest a few water changes with well ages SW
to be sure DOC
is as low as possible and ensure you are feeding with vitamin fortified foods. Mild maladies will quite easily clear up on their own providing the fish has the right environment and foods.
Aggression can cause scale loss but when I kept chrmois myself I found they where quite prone to scale loss. This may sound kind of silly but it was alsmost like shedding, don't know how else to convey it. They would regularly have varying color pattern and depths to the scale coverage giving the appearance
of not having scales.