My mandarin is now eating quite a variety now. I use single ingredient foods without gel binders. Bloodworms head the top of his favorites. He eats adult brine shrimp, mysis shrimp, plankton, squid, and shrimp. The key appears to be size of particles. He seems to eat any of those foods as long as they are chopped small enough. I pop out a cube of whichever one onto a plastic cutting board, allow it to set for a few minutes to get a little less hard, then cut thin slices off with a very sharp knife. This usually results very small particles.
Many folks think mandarins live mainly on amphipods but it seems they actually live on mainly copepods. At least mine seems to eat those with more vigor and consistency than amphipods. The size is much smaller.
My mandarin will also accept freshly killed chopped snails.
To enhance his food supply and to increase his easy access to the copepods I wedge small pieces of food into one of his favorite rocks. This seems to attract numerous 'pods
to his rock. Also, I've inoculated my tank with the 500ml copepod pack from Sachs Systems Aquaculture to give 'pod population a boost. I'm culturing my own pods
in several small tanks as well as in the refugium to add to the system as 'pod population density shrinks.
My little guy is doing wonderfully but if I had it to do over I'd feel more secure adding a mandarin after establishing a HUGE copepod colony in my tank. I wouldn't count on live rock to have all the variety of 'pods
already in it to produce the best results. Sachs Systems Aquaculture has lots of excellent cultures available. Everything I've ordered from them has arrived live and in excellent condition. If you order now I'd suggest the cold packs to keep your culture from boiling in the mail.