danios tend to stay in the upper half of the tank and pictus stay on the bottom. However, the pictus might move aorund the tank at night looking for food and might have a go at the danioss if they are hungry. As the pictus get bigger they will be more inclined to eating smaller fishes like neon tetras and anything small & slender that fits in their mouth.
if you feed the fish well before lights out at night, they should be fine.