Betta swimming odd?

I just recently did a complete water change in my betta's tank. I noticed tonight that he's having a difficult time swimming to the bottom of the tank, but otherwise he seems perfectly normal. To stay down he will wedge himself between a plant and the edge of the tank, almost like he's laying in the plant. I don't know if it's just stress from moving from a bowl to the tank after the water change but I'm really concerned about him. Like I said before other than swimming odd he's seems perfectly fine, no signs of a physical parasite or disease. I've read a few things online about a swim bladder disease; would that be caused from any stress? Should I not feed him tomorrow just in case he's constipated? Any suggestions?

It could be constipation. My male had a hard time swimming once. He was swimming sideways on his side. I fed him a cooked shelled pea and then I fasted him for 2 days and he was fine. Make sure the temperature is the tank is between 76-82F. When you do complete water changes make sure you use water conditioner and let the water become room temperature before adding the fish back into the tank.

Good Luck!

And for the first poster, it is OK to do complete water changes when you have a small tank or bowl. A 2.5 gallon tank will not cycle!!

Why did you do a complete water change? You are NEVER supposed to do a complete water change. You only do 15%-25% of a water change. If you change all the water, you take out all the beneficial bacteria to the fish and it can cause them to become severly ill and even die. Are you using water conditioner and bacteria supplement?