I know they should be in a tank with a fine, or rounded (in other words NOT sharp) gravel, because of their barbels they have around their mouths.
When I had corys, I had them with various Tetras, Zebra Loaches, a Rainbow Shark and Platies, and they seemed to get on just fine with all them. I had driftwood and plastic hollow log decoration things for them to hang out in, and they often did.
They are bottom feeders. Mine ate sinking shrimp pellets mainly, and probably bloodworm, if it managed to make it down that far.
What is your problem? Do they keep dying on you? It might help if you explain your current tank situation/conditions.