A note I post often when people ask about "schooling" is that schooling is a defensive strategy shown by many fish when they percieve a threat. In a crowded small tank, schooling rarely has any advantage, so is seldom exhibited.
You put ten Neons in a 24"/600mm tank with a load of other things, they'lll wander off on their own and interact little. Put exactly the same 10 fish in a 6'/2m tank with some wide open swimming spaces, you won't be able to seperate them.
So you are looking for species that are naturally "scared", and Rummy Noses, probably best fit the bill. However, they are a sensitive group, (there are 3 species), and will turn over in poor water conditions.