Unresolved Mandarin. Had him a week, would like a checkup.

You're going to have to learn to feed him/her at a feeding station, do the research. Some use blood worms as well as Nutramar's Ova. A Mandarins eats hundreds of pods a day and will quickly wipe out a smaller tanks pod population.
You might get some flak for not doing the research prior to the purchase of the fish, but all you can do now is learn how to feed the fish and what to look for. Persons at the LFS may not give you the correct information, so I would be reluctant to take their advice.
You have to feed the fish regardless of what it currently looks like so I would not spend too much time trying to get the ideal image, the horse is already out of the barn.

 

http://www.3reef.com/threads/mandarin-dragonette-fotm-may-08.47991/
http://www.3reef.com/threads/how-long-should-i-wait-to-get-a-mandarin.113142/
http://www.3reef.com/threads/mandarin-dragonet-feeding.117256/

 

The Ora tank raised( hatched) green mandarins have a better shot at living in the "average" tank than wild caught ones.. they are brought up eating foods other than pods.. but their diet needs to be high in nutrition and plentiful... as you already have been told your tank needs lot's of pods... I have a 30 gallon refugium that I have stocked repeatedly with pods from day one and still stock 2-3K pods monthly the bulk in the refugium .. the rest go in the ( 75 gallon) tank.... as stated above, train them to feeding stations. Mine will also eat newly hatched brine shrimp and frozen red worms if I chop them up into small pieces... .. she is a tireless hunter and much larger than yours and not at all shy.. she is the only fish in the tank big enough to turn on the bully yellow tail damsel.. more than once I've seen her peck the want to be bully in the nose..... from the time she emerges form her cave until she retreats after dark she hunts the rocks and substrate for pods.. constantly hovering and pecking.. mandarins move slowly but actually have a high metabolisim...copepods (tisbe) are very high in nutrition and their main source of nutrition... I leave one section of rock with a fair amount of hair algae.. this is her feeding station.. and if she sees the turkey baster she heads there.. feed any other fish first or they will harass her and make her stop eating.. a turkey baster with her food applied to the spot is the best way to keep her healthy.. also I have found that if you feed it as "night" falls on your tank, you will notice that they become more active during that transition period.. as that is when 'pods become more active... I can tell you from experience that you will spend many times over on food( mostly 'pods) for what you spent on the fish...and you will work very hard to keep it alive if it is to survive.. I love mine.. and keeping a healthy Mandarin was one of my goals when I started my salt water tank.. and she is one of the reasons I set up and keep my tank as I do..

 

I'm sorry but I dont think we can answer if your fish is healthy or not simply by a picture. You must understand what is required in order to have a successful mandarin. How big of tank?