I returned yesterday from a 5 day vacation, and I was unpleasantly surprised to find my Betta male had a large portion of his top fin missing. At first I thought he had torn it while I was away, but now I can't quite tell. I've never had experience with fin rot, so I'm wondering if it may look like this? He was fine when I left him, but the longest I've ever left him before was 2 days. He is still active and eating currently. I left a 7 day betta feeder in the tank given that I was nervous for leaving for 5 days. The block was completely gone when I returned. Also, I only have silk plants in the tank.
I did a 25% water change last night and changed the filter as well. I was debating another change and/or aquarium salt or melafix. I have both, but I don't know where to start here.
Anyone have any suggestions on how to help Leo after taking a look at these photos?