I would find a home for the mandarin unless he is an ORA and actually does eat prepared foods. My ORA doesnt really like prepared foods but I have pods
so all is not lost.
They can take up to several months to starve so you have some time, but not much. Once her tummy is caved in it's usually too late.
If you have a fuge or refugium you can add pods
to that and if you have ALOT of live rock you might be able to get some growing but thats a big maybe.
Good luck, and lesson learned, research before you buy. I got taken in by a "scooter blenny" which I was promised would eat anything. Well guess what, he only eats pods
too. LOL Luckily it only took a few months to get him on prepared foods but they are easier to do that with than mandarins.
Let us know how it shakes out.