SWIM BLADDER DISEASE
Swim bladder disease is not contagious, and can be caused by many things, usually overfeeding. The Swim Bladder is an organ located near its back. It helps the Betta to swim properly.
Your Betta may have gotten Swim Bladder Disease if you dropped him/her or handled too roughly. If this is the cause, it can not be cured.
When a Betta has Swim Bladder, he will either float vertically at the top of the water, or lie on the tank bottom. They will have difficultly swimming, and may or may not have a kink in its back to make it 'S' shaped.
Double Tail Betta's are more prone to Swim Bladder as they have a shorter body than singled tailed Bettas.
There isn’t really a treatment, most of the time, it sorts itself out. It’s a good idea to put your Betta in a tank longer than deep, or lower the water level. This helps them to be able to reach the surface.
Fast your betta for 24-48 hrs, and the following day, offer a pea.
Sometimes Bettas will live with SBD for their lives, but don’t worry: they aren’t in pain, just have a little difficulty maneuvering.