Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
I do not think Pencils and Sanios will school.
Danios are highly active, zipping from one end to the other of a tank, and while they do roam all over, they tend to be upper half fish.
Pencils are the opposite. Not exactly sedentary, still, they are a lot calmer than Danios, and they tend to be a bit lower in the tank. Not bottom dwellers, just not usually all the way up at the surface as much as Danios tend to be.
Probably a good combo, though. Adds interest in more areas of the tank.
I would bulk up the populations of the species you have before getting more species. Most schooling fish are better when you have a dozen or more, when that is possible.