Mine really love bloodworms, but will also eat flake. I keep two of them, and they seem pretty happy. I had one alone before, and he wasn't in any way stressed. Two are much more fun, though.
Whatever you do make sure that the tank is really well covered. I lost my first one because he jumped out of the tank. Give them plenty of plants and hiding spaces, too.
I keep mine in a tank that's a little too small for them, but they don't seem to mind. There are few other fish in the tank with them, and they seem to do fine, as long as my cat doesn't torture them.