a mandarin needs pods, however, they can be trained to eat mysis with a turkey baster if u stop flow during feeding so they can see the food.
there is a big difference between overstocking and over crowding a tank. over stocking means the tank can not handle the bio load of the fish and then you get an ammonia reading.
over crowding means the fish are mad at each other and fight and do not get along with each other.
if you work on your bio filter, you can add many fish, as long as the bio filter can handle it.
I have a 46g tank. I Have, 1 male and 1 female captive bred reidi seahorse. 2 false perc clownfish. 2 PJ cardinals fish. 1 diamond goby, 1 scooter dragonet trained on mysis, 1 yellow wrasse, 1 coral beauty....1 algae blenny....
it sounds like too many fish, but i never get a nitrate reading over .20 NEVER an ammonia reading.
This is because i have lots of filtration that can handle the waste. I'm to tired to type it all in right now, but all fish get along just fine.
So the bottom line is this, if you can train or feed the mandarin then get it, but its not like feeding a dorky chromis flake food.