They usually only eat pods, better to keep in pairs but not really easy to keep. I've always wanted one but heard horror stories of them wasting away. Maybe if a fish store has one eating prepared already.
Mine eats whatever food floats in front of it and also grabs at the sand. I don't know about in a 30 because I have a 125. Although I do have to make sure that there is food that goes down to it because it usually does not come off the bottom.