Its alot of money to try and help. I know where your coming from tho. Every time i look at mandarins at lfs so many are thin and mis fed. I have 4 mandys and 3 scooter blennys half are bc I wanted to help. Dont get me wrong I love them as fish, but had they been plump and healthy idk if I would have that many lol. The big diff w them tho is most lfs dont feed them the correct food. They will eat if fed the rt stuff. W the tang in my experience there not picky eaters, mine are pigs! So something else maybe wrong if it wont eat anything