Make sure when you buy this fish it will eat at the lfs.
I take a small pipette, and suck up either frozen brine shrimp, or live baby brine shrimp as mentioned above, then squirt a few squirts of food at one end of the tank.
The other fish are so preoccupied at that end eating, it is pretty easy to squirt some down to the Mandarine. He get's his share that way