My Betta Fish's Pectoral Fin Has Suddenly Changed Shape

my betta fish's pectoral fin has suddenly changed shape. there are no other fish in the tank and the tank is clean. i've got no idea what could have happened. the pectoral fin was first a fan shape but now it is a leaf shape. I am really worried about him. does anyone now what it could be?

 

Can we see pictures? Of the tank and the tail?
Tank size?
Heated?
Filtered?
Cycled?

 

Have both of them changed or just one? It could be from clamped fins which indicate stress if it’s both, or possibly an injury if it’s just one. Or are you maybe thinking of the caudal (tail) fin? Young veil tail bettas will have their tail fin change from fan to leaf shaped as it grows (could also be seen if he’s regrowing fins after fin rot).

Either way, a picture and the tank size and water parameters (ammonia, nitrite, and nitrate) can help us identify what’s going on so you can help your fish.

 

My tank is a 23L fluval edge, it is heated, it is filtered, it has been cycled. I think he might have just hurt his fin because it looks a lot better than how it looked before. (it was just one that looked like a different shape btw)

Also the water parameters are all what they are supposed to be
Here is a picture of my tank (hard to get a good picture with a computer)

sorry I posted 2 of the same pictures

 

It looks like it's clamped or he has fin melt

 

I am happy to say that his fin is back to normal. I am so glad it is because I was starting to get really worried. thank you so much for replying to my thread.