Foxface has something wrong with his mouth

[Seventy7INa45]

I have a Foxface in a 50 gal tank. The other day, I noticed that his mouth looked different, almost like his teeth were out. He still eats and his colors are good. Does anyone know what would cause this to happen? I added a picture below of what it looks like

 

[mr_X]

i don't know, but you better do some water changes and get a handle on that algae! cut back on feeding as well. every other day at least.