Betta's fins shredding?

[AriaRose]

I'm just wondering if anyone might know what's going on with my bettas fins, at the bottom they look like they are shredding. There is no discolouration where they are shredding, they've never looked like that before. I've had him for 7 months. Thanks

 

[NickAu]

It looks like fin biting

 

[Demeter32]

Did this suddenly happen over night or was it a slow process? If it was sudden then Nick might be right about the biting. If it was slow then I'd lean towards fin curling.