Yes, mandarins are one of the most difficult fish to keep and its just like Koko said, they mostly live on copepods. That is why you are never, ever supposed to put them in any tank less than 6 months old. Everywhere I have read says never to keep a pair in anything smaller than a 125 with tons of live rock. But I think I can get away with it because this tank will be tailored just to them. I am planning to stuff tons of LR in there and make "pod piles." Those are areas of LR rubble that you put food in (where the fish cant get to them) and the pods feed on it and multiply. You can also order pods online which I plan to do. I may eventually add a refugium because that will give the pods even more area to live without being eaten.
As you can see I really like to do things the hard way! When someone tells me I cant do it I get all the more determined to do it, and do it successfully!

One side note, some mandarins will take to frozen food. My friend and I are keeping an eye out for the mandarins that come in and will eat frozen. I will still of course culture the pods but its nice to know I can give them some other food as well.
I set up my tank tonight. I am hoping to add some live rock to it by the end of the week. I'll post photos as I go!