Take the Mandarin back to your LFS before it dies. I know you are not going to want to hear this but trust me hear are the facts for keeping any dragonet.
At a minimum this is what you would need:
At least 100 pounds of liverock.
A sufficent and stable pod population.
And the most important is to have a tank that is a minimum of one year of maturity(one full year after the cycle has completed).
And yes, if you do a search on this website I'm sure you'll find someone who claims that they have a healty Dragonet that lives off of frozen foods but you have to keep in mind that is pretty rare. If you don't believe me call around to your LFS's and get a poll from them. Chances are they'll just repeat what I just said.
No hard feelings, Dragonets are cheep and easy to come by, it's just that it's really, really hard to keep them alive and happy.
They shouldn't just survive but thrive.
And I'm in no way a PETA person just trying to pass down wisdom.