I know I am in rthe minority here but I have had a Spotted mandarin in a 10 gal tank for over a year now.I do not propose anyone going out and doing it though. I ha d a 10 gal tank with 2" sand bed lots of chaeto and Calurpea in it as well as it was just about packed solid with live rock in large as well as rubble. It wa used as a tank to keep some macro algae in, the live rock I acquired alive and the sand alive...just incase. It had on a AC hob filter which also had rubble in it. It was probbaly like that for close to two years. Always adding some live rock or removing live rock for varous projects. There wa a bunch of small serpand brittle stars, and I did pitch in some mud whelks and ceriths and a couple of blue legged hermits. I was offered a mandarin from a person that had one that attempted to keep it in a unestablished tank. I placed it in this tank (hardly any room to swim) merely as a temp home for it until I could find someone to take it or until I oculd carry it to the lfs I patronize. Anyway its been there ever since and doing just fine. Still have tons of pods which repro al the time. The fish does fine and it really does not need much room for swiming. So I guess its safe for me to assume this is where this fish will stay as it sure does not look like its depeleting the pods. I had thought about trying to breed them, but talked myself out of that as its doing just fine byiself the way it is so why mess it up.