I see he's a new addition to your tank. While I've never seen a happy, settled fish swim up and down like this I have seen sick, new or nervous/agitated fish do it. It doesn't sound like he's sick, so I'm wondering if he might just be a bit nervous in his new home. It's a good idea to test your water, as hcgirl80 said, just in case. If all is well with the water chemistry, he might just need some time to settle in or a few more decorations/plants in the tank to feel secure. Gouramis like the water to be fairly gently circulated and often appreciate some plants floating on the surface, so if you can provide some shade and turn the filter down a bit (if it's creating a lot of current) he might settle down.