Need help with betta fish?

How long have you had him? He may just need time to adjust to his new environment. I remember how scared I was when I got my betta, and he didn't eat for almost a week. Bettas can actually go about 2 weeks without eating so I wouldn't be alarmed until that week and a half mark. There could be several other contributing variables also. For example, the temp. of the water should be between 75 and 80 degrees, cold water suppresses betta's appetite. Another thing could be the food itself, my betta never went for the pellets, he actually wouldn't eat anything but the tetra color enhancing flakes. So my advice to you is to check the temp., and experiment with different foods, but if this doesn't work than just give the lil guy time to adjust.