Crowntail Fins Looking Lumpy On Ends?

*Sorry I don't have any recent photos I can post right now, I will try to post some in a few hours*

I don't know that much about different betta tail types as my last 3 have been veil tails, but I currently have a crown tail who's fins have started looking a bit lumpy on the ends, is this normal?

He's always had naturally dark tips so it's hard to tell if it's fin rot, and I know that crown tails can curl from higher pH (correct me if I'm wrong). Should I be concerned about the lumps? It almost looks like some of his tips are knotted...

Here's the closest picture I could find to what I mean (not my fish, from Google), see how the ends look lumpy and kind of knotted:



And here's my fish a few months back (so you can see the darker tips):



I also have what I *think* is a delta tail elephant ear who bites his fins (can't blame him, his caudal fin is HUGE) so I don't have much luck in keeping bettas' tails looking nice!

This is my fin biter, I've tried everything to get him to stop in the year I've had him... this was taken a few weeks ago, you can see the nice big chunk he's taken out of the bottom of his caudal fin:

 

Here's a couple of shots from today:

 

Can anyone tell me if I should be concerned about this? The only information I can find on Google is about fin curling but this seems different to that?

 

I think it might be normal and maybe a result of the water, similar to curling fins--my crowntail has at least one "knot" in his analfin. It's kind of hard to see it normally (and to get pictures, since he's so wiggly):




He didn't have these knots in his fins when I first got him from the PetSmart, but he's been acting fine even as the knots showed up. I'm inclined to believe that I don't need to worry about it. He eats fine and comes to the tank to greet me even if I don't have food and sometimes we make silly faces at each other, and the knots don't seem to be bothering him at all.

 

The curling is genetic. I had a betta breeder friend rehome one of his crown tails to me because of the same issue with the ends curling. He lived a full happy life

 

Phew that's a relief! The poor guy looks like he's been through the wars since I got him! But I guess it's just a case of aging, water and genetics. Guess I can't expect a $10 betta to be show quality!