Have you looked into any of the Aspidora species? I find they are a hardy fish and most stay to the 2 inch or smaller range.
We have 3 Aspidoras fuscoguttatus (I think) and they are great to watch. They are like little water chipmunks, fat cheeks and mouth always going. A very peaceful and personable fish for a community tank.
Here is a pic of one of our little guys
