betta with "holy" fins

[ducksarefun]

hehe no, he hasn't been "touched", but I noticed this morning that Mufasa has some holes in his dorsal fin. They aren't on the edges, but in toward the middle. They are perfect ovals. He has one in the middle of his tail fin, too, that was there when I bought him- also a perfect oval. The only thing in the tank with him is an apple snail.
Any ideas what causes this ?

 

[Iggy]

My betta's sometimes get holes and tears in their fins. It does happen, maybe from rubbing against/ontop plants, or just normal wear & tear. It it does not spread or turn whitish, it will grow-out.

 

[Dragonett]

Mine get them too, although they heal themselves within days.