zebra danios are really active zippy fish, I find I like them best in a school of their own or they tend to create traffic jams and look chaotic in smaller tanks.
If it were me I would do either 8-10 danios or 8-10 tetras and a small group of 4 to 6 cories on the bottom, or alternately a group of small loaches to balance out the top and bottom of the tank.
That said my orange von rio tetras seem to stick to the bottom levels of the tank more than the top, so maybe 8 danios and 4 of those would work.