Regardless of plants, you want to keep the surface of the water moving or else proper gas exchange cannot take place and your water becomes stagnant. If your filter does a good enough job then you might not need an airstone.
If your tank is tall and skinny, with relatively little surface area per unit volume, an air stone is probably a good idea.
If your tank is short and wide, with a relatively large surface area per unit volume, an air stone is probably not as important.
Now, you don't necessarily need and air stone to provide current and surface agitation. You can get that using filters and powerheads too. But, it's best not to completely rely on your plants for your tank's oxygen needs. Plus, providing surface agitation and flow have other benefits as well.
Besides, White Clouds and most danios come from cooler moving water with higher oxygen content. They'll appreciate more oxygen and more flow.