It looks slightly over stocked the tank.
Need to look at your water stats in ammonia, nitrite, nitrate, and ph.
Is the fish also flicking and rubbing.
Any red sores of red pink prick marks on the fish.
Does the body look pale, or greyish white with excess slime.
Are the gills red and inflamed, or swollen, pale with excess slime, look like there bleeding.
Does the fish look bloated or skinny.
What does it look like when your fish go to the toilet.
Is the anus enlarged or red and inflamed.
is the spine bending.
Is the belly sunken in.
The symtoms point towards bad water quality, external parasites, internal parasites.