Yep I definetly have gravel, because A) it was free, B) when I first started looking into fish keeping and reading about it, I read about how anaerboic (sp?) bacteria and gases could build up and poison the tank unless you had a fish that would constantly stir up the sand, which I wasn't planning on, C) I put in gravel and got fish and now that I have cories would like to change but don't want to mess up the equilibrium of everything as all the fish seem to be doing quite well, even the cories, (though i do think the gravel is a bit big for them, it's not huge, but it's not very small and fine either, poor cories, guess they'll have to wait for a new tank before they get sand, (which may or may not be a while we'll see if I get a place off campus next semester, or next fall)