I think so. I would only add them to a RSM that was well over a year old though. Also having a Refug helps!!! I had mine over a year now and he is good. I grow cheato in the back right chamber on my RSM250 with an LED light
They r small so size requirements check. Now constant food source. The pods live in sand. Rock. Sump. Etc. Do u have enough hiding places for their dinner?
I have a mandarín in my RSM 250 ... it has been 7 months here and what I did is I seeded pods to the mail tank and it worked perfectly... I seed it each 3 months or so with 2000 pods from reefs2go.com
I had one in my old 55 for 2 years with just a HOB filter and HOB skimmer. It did very well and grew quite large. No reason the RSM would be any different.
Another thought... is an ORA Mandarins - at my lfs about 5 times the cost of a regular one... but maybe worth it - as the odds increase of success if he is already eating frozen & dry food. This is what I have been thinking about doing... though no guarantee - I do thing this increases the chance of success.
all of ORA’s captive bred mandarins will accept a variety of prepared frozen and dry foods upon acclimation to their new tank. They may be offered Nutramar Ova, finely chopped Hikari Frozen Blood Worms, fish roe, frozen or live baby brine shrimp, frozen daphnia, and New Life SPECTRUM Small Fish Formula pellets. Some have also shown interest in Cyclopeeze.