Lol yea...It would work in a 40g MINIMUM though. If you get a nice pair of rams or apistos you won't be dissapointed in the 20. Especially if you add about 8 x-ray tetras and 4 - 5 marbled hatchetfish. (plus your pleco)
Oh sorry I should probably add this. As allaboutfish said earlier, adding an extra female to your ram or apisto group will result in less stress and more productive (and more) spawns.
no thats not whaat i was saying. i was saying if they did the 2 different dwarfs they should do 2 females. ive heard if you keep a trio of dwarfs one female gets killed of.
OHHHH i see lol my bad. It really depends on the fish (as always), it has been my experience that having a trio is more benificial to the females, letting tham have a break. But, as always, it depends on the fish, some males are intolerant of any females at all, and some females don't tolerate other females with their male, and some females hate all males lol.