kyrie_eleison,
I wouldn't make such blanket statements about mandarins not eating brine, I've gotten them to eat frozen brine and mysis fairly easily on more than a few occasions
It's kind of like seahorses, you need to feed them lots and have no fast moving fish that will outcompete them for the food. Also, yes, they will need a large well established tank with plenty of worms and pods in order to do well long term.
BTW there are certain words, that while not in the censor list, are best not used