I got a baby betta from PetCo (didn't realize at the time they were too young to be sold?) last July for my husband. It was a cute little black, red, and translucent thing. I thought for sure it would be a female veiltail, but we got a boy. Looked liked a veiltail still with something like a butterfly coloring, but he's still changing and growing in color and tail. In the last month or so, his bottom fin (I believe it's called the anal fin?) jutted out in a weird shape and his back fins split a little. In the last week, that weird part of his anal fin split as well.
Here is a video of him