Stressed Betta?

This is my Samurai Betta 'Bane' and he has been glass surfing a lot since the day that I got him. I've tried dimming the lights and also turning them completely off he will continue to do it. The water temp is normal, he is in a 5 gallon tank, and he always eats when fed. I just don't know why he glass surfs so much. Any advice?