Hi all. This is my first time owning a betta, responsibly. I got this guy about a month ago from Petsmart. (I know, but there are literally no other options where I live, aside from Petco). He seemed a bit small when we first bought him, so I assumed he was a growing boy.
However, last week I noticed some jaggedness to his fins. He shares a tank with a nerite snail and I use only live plants, so the jagged edges were concerning me. I'm actually helpless at seeing the signs of rot, I've watched countless videos and have seen countless photos. The consensus is the fins start to blacken, and it looks like there might be black on the tip of his back fin. I could also be paranoid.
So, is this fin rot or do fins start to look different as the betta matures? For reference also, petsmart had him listed as a Dumbo Halfmoon. The first two photos were taken when I first brought him home. The last two photos are from today.
P.S His name is Billy the Bandit. He seemed like a trouble maker once he was in his new tank, so I named him after my grandpa that passed last year, who was also a trouble maker.