I'm not sure I can be much help, as I'm new at this. I started my first saltwater tank five months ago. I purchased a mandarin for my 2nd fish in my 75g. I didn't know much about them, just loved how they looked. I got lucky and had lots of pods and live rock in my tank already. But that little mandarin decimated the pod population pretty quickly. Determined to keep him, I did alot of reading.
I created a pod breeding ground in my refugium. Once per week, I trade 2-3 pieces of live rock from my display. He has a ball for a day or two eating all the new pods hiding in the small holes in the live rock. After a week, the live rock in the refugium has lots of new pods living in it.
I'm not sure if I'll be able to keep him long-term, but it's looking better week by week. He was getting skinny about two months after I got him and almost took him back to the LFS. He wouldn't touch any frozen food. So I got another powerhead to increase current and tried frozen plankton. He went nuts! Just kept chasing them around and eating them. Wasn't long after that I got him to eat mysis shrimp, blood worms, and brine shrimp. Now he doesn't look skinny at all. He hunts all day long for pods and usually eats when I feed the other fish frozen foods. I'm not sure if the additional current made it look like the plankton was alive cause it was moving around alot, or it was just coincidence. Either way, he finally started eating frozen foods.
I realize that the frozen food doesn't supply him with all the nutrients he needs, so I still do what I can to keep the pod population at a good level. I found that feeding the refugium live phytoplankton helped alot. Give it a dose and a day or two later there are lots more little pods in there crawling around.
HTH. I am still learning, but really enjoying the switch from FW to SW.
Good luck!