Gill Cover Re-growth ?

[freshfishies]

Hey all
Went to visit my Mom the other day and one of her angels is missing a gill cover. There isn't really any aggression that I've seen in the tank, but we separated it from the others anyway.
Has any one else every experienced this? Anyone know if it will grow back?
Thanks!

[torin32]

just missing no sign of fungus or anything like that no fuzz white stuff.  If not maybe hit a rock while swimming when it got scared very strange.  Mix melefix in the tank and go from there antibiotics to help heal.