Poor guy. The betta shouldn't be nipping him at all. You may think things look fine but your poor Cory may be really stressed because not only is he alone in a small tank, but he is being harassed by your betta.
My tank has gravel and the cories are just fine. I love cories, one of my favorite fish…They are very curious fish and love exploring with their buddies. Because of this, I would never put them in anything less than a 10 gal tank (a heavily decorated one at that).
In a tank your size, only tankmates can be snails or shrimp. If your betta doesn't kill them, shrimp will be great at cleaning up leftover food.
Last edited by Alex09; 02-18-2011 at 08:45 PM.