An Issue With Floating

[randomtyping]

I have an issue with my betta. He can't seem to stop floating. It's not because he's lazy. He struggles, and jolts down to the bottom of the tank, trying to get under the plastic substrate. A couple of flutters, and he just rises back up. Sometimes when I get home from work, I see him under, only to realize that he is underneath a thin plastic plant. It's the only way he can stay under.

So what's wrong? Does he have a parasite? I don't see how.
Would it have something to do with the hardness or temperature of the water?

 

[Colin_T]

He either has air in his stomach from eating too much dry food. Or he has a problem with his swim bladder and it isn't regulating properly thus preventing him from being neutrally buoyant in the water.
Try feeding him on frozen or live food for a week and see if it helps. If it doesn't and the problem is the swim bladder, then there isn't much you can do.
Some people lower the water level in the tank and this can make the fish feel more comfortable but the less water the more often it will need changing.