I know what you mean about alot of space for one fish, but there isn't anything that i can keep with a male Dovii in that size tank, and everytime i see pictures and videos of members Dovii, it just makes me want one even more.
So it's going to be a male? 6x2x2 is not a lot of space for it, but you may want to ask Balton777 or JK about their personal experience.
Edit - check this thread http://www.monsterfishkeepers.com/forums/showthread.php?271513-I-think-I-m-going-to-sell-my-Dovii-

