They are a very shy fish and never get big. If you are going to keep them with more aggressive fish you need a tank that can support them with algea and pods as they will never get to the food you feed the tank as the other fish will scare them off. I would say anything more than and including a blenny/clown would over run them. If you keep them in a very calm tank, they have a fair chance of learning to eat what you feed the tank and do better.
They are a difficult fish to kep on average. If you have a stocked tank with enough life to support them then you will most likely not see them much which is a killer for me. If your tank could support a Manderin, then a ainford would be happy I think.
Also, sometimes a rainford can hold his own pretty well. I have seen one or 2 that will eat fine in a small stocked tank and mix it up with the other fish, but would consider them a rare find.