I think fasting him might help as well. But he could have something parasitic going on in his body.
Only saying that because I've never seen a betta that bloated before...
Only saying that because I've never seen a betta that bloated before...
There is a few reasons that he can be bloated.
Overfeeding or internal parasites.
How many pellets or how much flakes she was feeding him?
With internal parasites he will have white,clear stringy, wormy shape poop.
Did you see his poop?
If he bloated from overfeeding than you need to fast him for a few days and if it not helps than Epsom salt will. Not aquarium salt though.
If it internal parasites. You need medications. Make sure in the medications if you can find for internal parasites not for external.
If he can eat medicated food like someone wrote. There is anti parasite food. Unfortunately don't know brand .
Now if you will sure it internal parasites you can definitely start him on Epsom salt . Not it will help with bloating and clean his system. But Epsom salt without medications won't treat it.
For Epsom salt you can start from2 tsp/gall. Pre mix it in the one gall jug for the right dosage. Make changes every 24 hrs.
Not sure how big is his tank. You can qt him in smaller container or just lower the water in the tank so you can do daily water changes.
How long he is bloated like that?
Are you still feeding him? How much?
I hope he bloated from the food .
Internal parasites very difficult to get rid off. But it always good if fish eating it helps to pass parasites out..
EDIT: When you do water changes with salt you need to do 100% water change