Might be swimbladder

Question
Hi. This is Linda. Our Betta is starting to swim on his side. It seems like his rear end is up when he swims. What should I do. Thanks Linda

Answer
Hello,
Swim Bladder is caused by poor diet, and overfeeding.  This leads to constipation, then SBD.
You did not mention the size tank he is in, so I have no way of knowing his living quarters, and cannot give you good information concerning his water.  If he is in a small tank with no filter change all the water cleaning his tank, and refilling it with the same temperature water he was in.  If he is in a filtered tank, do a water change.  Make sure there is no ammonia in his water, and use a good water conditioner.
Cook one frozen pea until tender.  Remove the outer layer, and cut the pea into tiny pieces.  Feed the pieces to your Betta one piece at a time making sure that the pieces don't fall to the bottom of the tank.  Feed him nothing else for two days.  He must waste.  If he refuses to eat, he will need antibiotics.
Kanamycin, is very good for swim bladder, but sometimes hard to find.  If you cannot find it buy Tetracycline, or Furan 2.
Do not let this linger on, as his condition will get worse, and then lead to damage of his swim bladder, or kidneys which are impossible to cure once the harm is done.
When he gets better, feed him small amounts 2-3 times a day.  Never feed him a big meal once a day as his tummy is the size of his eye.  Vary his diet....Betta Pellets one day, Betta Flakes the next, Daphnia the next, Bloodworms once a week, and a cooked pea once a week.  On the day you feed him the pea, feed him nothing else.  This is to help him clean out his system.  For one meal feed him 2 pellets.
I hope the little fellow pulls through, and if you have other questions write back to me, and I will try to answer you the best I can.
Lynda