Beware, Platys often are pregnant when you guy them. Ask me how I know! Maybe some white cloud minnows? 5-6 would do.

Hi
I found a website called AqAdvisor with an interactive part which lists around 900 species of fish and inverts. Just fill in the blanks and it will calculate
proper stocking levels. Even gives filtration, water change schedules. All you need to know are the dims of your tank. gary

I'd second the white cloud mountain minnows. I recently bought a few to add to a tank I maintain at my college, and they go well with the zebra danios and the two species of tetra I also added to the tank. The white clouds are reddish and white, nice looking fish, but stay about the same size and shape as zebra danios. If you want something a bit different looking, you can always get a small school, maybe 3-5, smaller tetras such as blackskirt, lemon, black phantom, or bleeding heart tetra (I have the first two in the tank at school). Tetras might be a bit nippy if you have the long fin zebra danios, but if there's enough space they should be ok.