sand as substrate for gouramis?

I had a 29gal tank with 4 gouramis in it, decorations including artificial plants and gravel. I recently purchased a pre-owned 90gal tank that had sand, artificial plants, etc. What I was wondering was: can gouramis live with sand without eating it or etc? I ask this because in the 29gal, they would eat fallen food from the gravel & would simply spit the gravel out. With sand, would they eat the gravel alongside the food?

Thank you for the help =]