I know this isn't what you were asking but.....I've had success feeding mandarins by placing a small jar (small enough so larger fish won't go in) on the sand, and squirting frozen mysis shrimp in it through a turkey baster. Once the Mandarin figures out there is food up for grabs, it'll go back there to check it out frequently.
Eventually, your larger fish will figure out that they can get the food out by flapping their tail near the jar and the mandarin won't get much, but it'll buy you some time.
Dunc
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