As a surprise Christmas gift, my wife got me a pair of mandarins from Biota, which I had been hinting at for about 2 months, and I had actually been establishing copepod and amphipod colonies in my reef for quite a while prior to that just in case. They arrived to my complete surprise the Wednesday before Christmas late in the afternoon on a day that was brutally cold here. Upon opening the box, I noticed that the bag was cold and they were not swimming but rolling around looking pretty much DOA. The acclimation page on the Biota website stated to float them then put them into the reef, no acclimation beyond that. So I let the bag float for 15 minutes, opened it up and put them into an acclimation chamber in my reef. And to my total surprise they were both moving about immediately. Everything I have read has indicated that they are small, but I really wasn't prepared for just how small they are. In fact, the female somehow managed to get out through a tiny gap in the lid the first night. I decided to let the male loose the next day and didn't see the male for a week in the 50g cube they're in. However I saw them both for the first time today, hunting right next to each other and considerably larger in size. And utterly spectacular. I haven't seen them eating pellets since they hide most of the day, but clearly they are eating well. So if you're considering picking up a pair, I highly recommend.