Betta Fish: Why are my Betta’s fins ripped?

Hey everyone, I need some advice. I’ve had my betta for about a month, and I’ve noticed his fins look ripped. I do a weekly 30% water change, and his water parameters were fine last time I checked. He’s very active, but I haven’t caught him nibbling on his own tail, so I’m not sure if that’s the cause. I’m also wondering if it could be due to the rocks in his tank. He was fine 4 days ago.

Here’s what I’ve considered so far:

• Tail Biting: I haven’t seen him bite his tail, but I know this can happen due to boredom or stress.
• Sharp Decorations or Substrate: I have some rocks in the tank, and I’m wondering if they might be tearing his fins when he swims too close.
• Fin Rot or Infection: I don’t think it’s fin rot because his fins aren’t blackened or discolored, but I’m keeping an eye on it.

What can I do to help his fins heal, and should I be doing anything differently? Any advice on preventing further fin damage would be appreciated!