Ive never kept them but Im pretty sure they are not really shoaling fish. Water parameters can affect shoaling fish too. My group of ember tetras have stopped shoaling all together, shame. They did look amazing.
Small numbers of fish normally don't shaol very well, except when frightened. If you want shoaling then you'll need a large tank with a couple of hundred fish. They then shoal really well.
i have 4 and they must hate the sight of eachother. They hang out in each corner on the aquarium lol. My serpaes and neon dwarf blue rainbow fish love to school tho.
Any of the micro-rasboras shoal well. Boraras maculatus, B. brigittae, etc. Cherry barbs are not a shoaling fish. Actually, they prefer to be solitary or kept as a breeding pair. This makes them an awesome centerpiece fish for nanos, especially a breeding pair. You can treat them kind of like how you would treat cichlids in a larger tank. Your dither fish would then be a boraras species, followed by a pygmy corydora. You can then create the illusion of a larger fish community in a smaller tank. That being said, my 36 cherry barbs were raised together, and don't know the difference, so they often cruise the tank together and form feeding frenzies during picture time. But, my cherry barbs aren't normal.
My Golden Barbs don't school tightly, but they are always in the same region of the tank. If I walk within a metre of the tank they all come to the front awaiting food though!