This is Aria, a female double-tail plakat betta a recently adopted from a wonderful breeder in upstate New York. Aria has a deformity or injury to her jaw that prevents her from closing it. She can eat fine, but requires a little extra TLC, and a special diet. Since I run the betta rescue, her breeder thought I would be a perfect home, and when we visited together around Thanksgiving, I left with two lovely "cull" fish!
I'd like to encourage anyone considering buying a betta from a pet store, where the animals tend to be sorely neglected, diseased, parasitized, and from poor stock to first consider seeing if any breeders live locally, and if they have any "culls" for adoption. Culls are unacceptable for breeding and would be euthanized without your help! They are usually healthy but have some minor defect, like uneven finnage, a slight spine curve, etc. But they certainly make perfectly lovely pets!