To me it looks like it just missing patches of slime coat. Clean water and salt will get him back to health. Oh, and make sure you keep the water clean.
I have a similar problem with a Green Texas little growths in and around it's mouth it appeared when they started spawning I also treated for cotton mouth and with an anti bacterial and fin rot treatment on advice from LFS by then it had started to appear on the nostril then treated with melafix for seven days I did 30% water changes for 3 days between treatments and I have removed all of my gravel I then put him in a saturated salt solution and this got rid of the growth coming from the nostril but didn't really have an effect on the growths in his mouth his behaviour is normal eg- aggressive eating well spawning regularly View attachment 765224View attachment 765225View attachment 765226View attachment 765227
He's had this for about 3 months