I went to Russ's (Masterswimmer) place yesterday and I told him about this one guy who has 14 fishes in his nano tank. And his Mandarin pair was spawning. It's unbelievable and I wouldn't recommend anyone to try it.
http://www.nano-reef.com/forums/index.php?showtopic=85082
http://www.nano-reef.com/forums/index.php?showtopic=85082