I've got some experience with this. I picked up 3 little indos a while ago and put them in my 120g tank, which some would say isn't a good idea because they might have trouble finding food. However, all showed great color and personality, even coming to the front glass to beg for food. After I added some larger fish, I moved them to a 20g on my desk to grow out a bit more. Guess what? I never see them because they always hide under my driftwood. I think it might have to do with competition. In the 120 they were with lots of smaller fish, like young clown loaches, always out and about. In the 20g they are alone.
I'm going to try adding some small fish with them in the 20 to maybe make them more comfortable. I'm sure it woudn't hurt for you to try the same.