why'd you call this rainbow mandarin? I thought we had a new mandarin or something.
Either way, You may have squashed your mandarin, things happen. He may be trapped, the same thing happened to me, and this came after a lettuce nudibranch and a jawfish dissappeared (didnt jump) Then, it came to be it was hiding between the heater and the glass in the back corner (you dont think to look there.) So who knows, look around, and good luck to ya!