New-ish Betta losing scales on face -- any thoughts?

[Ariel347]

Hi. I got a delta tail male betta fish 40 days ago and have noticed that he is loosing color and some scales in the face. His body appears to be fine and his behavior is normal --he's very active and has a great appetite. He is the sole fish in a 13 gallon, well-cycled tank along with with 1 mystery snail --it's planted, heated, and filtered. Nothing on his face seems swollen, and I don't see anything in the tank that he could be injuring himself against. I also wonder if he is still adjusting and it could have been caused by stress...

I posted a pic of what his face looks like. I'd appreciate any feedback you'd wish to share. Thank you!

 

[JuiceBox52]

Do a 75% water change. I dont know what causing it but keeping the water clean will help it heal and not get a secondary infection

 

[Essjay]

Is there any decor in the tank with small holes? Bettas have been known to damage themselves by trying to squeeze through holes that are too small.
If this is the case, water changes will keep the water clean as it heals.