Sexing dwarf Gouramis- (for dude with the unsexed blue dwarf)
Mostly, females are colorless (grey) or have only a slight dull yellow/brown pattern. There are some reports of colored females in the powder blue morph so here's how to be sure
Female Colisas behave very differently from males, but that is the hard way to tell.
The easy way is to look at the anal fin (the one just under the "tail" or caudal fin) if the tip has a very bulgy, pronounced rounded edge, almost like a sphere, that pops out from the fin, its a female. Males have a bulgy rounded edge too but it is much less pronounced
Still not sure? Females are always out and about, searching, foraging, and having a good time. males tend to hide behind a plant and just kind of stay out of the way. They are also slower to come to the surface to feed.
STILL not sure? Get a male (just go with another morph so you can be sure its male- remember, the others have plain females!) and put it in there. If your current fish goes up to it and starts feeling it with its feelers and trying to get its attention, you have a female. And if your new male likes it, he will turn sideways and do a little dance where he wiggles his body. Its quite entertaining.
On the other hand. If they both do the little dance, then bite eachother, they are males. Only the male will dance. If the other fish is female it will just watch.