It was my dream fish too, but I held off getting one until I found one that ate something other than live food (was supposedly eating oyster feast).
What's hard about these fish is that they are almost like seahorses, where they are very finicky, eat constantly, and eat live foods. Even with a large copepod population & refugium, it can run out quickly (can eat 2,000+ copepods a day!).
Plus, even if they do eat frozen foods, they aren't aggressive feeders like all the other tank mates. You can have a little plastic cup/box with a hole for the mandarin to go in and eat without competition or spread small foods on the rock.
I've fed it frozen nutramar ova, brine shrimp, cyclops, cyclop-freeze, & mini mysis. I've seen it eat mysis, but don't know if it ate the other foods. He's fat and I've had him for 7 months so he must be eating something! I added him when my tank was 6 months & had a good copepod population.
“Success is walking from failure to failure with no loss of enthusiasm.”
- Winston Churchill