Could it be parasitic? They moved in each pic.thebiggerthebetter see anything like this?
agreed with 99.9% of the cases of sensitive fish, that's why I mentioned meth blue instead of anything else, extremely easy on the fish and if it is only a scrape that will help stave off secondary infections.Could just be a scrape. I'd stay on top of water changes and increase flow if possible. Blindly medicating tigrinus cats is a huge no-no.
FWIW I must side with shookONES when it comes to any fish.
One puzzling facet of what we are looking at is that there is no sign of inflammation, nor is the fish looking sick... as if this is not an illness or an illness in its latent stage / form.