My Upside Down Catfish wont eat food on the surface, any ideas?

I recently bought a beta, a glow light tetra, and an upside down catfish. My upside down catfish seems to be healthy, he swims around, and chases my beta around the tank. However, when it comes to feeding even when the light is out and food is on the surface, he will either swim ped it, or he wont swim to the surface. So far he if fine just eating the stuff the stuff that falls to the bottom of the tank, and algae from the tank.