Get Magagascan if you can - they will kind of shoal but its not quite right each species has a shoaling behavior which makes them feel safe and secure which in a healthy tank is not always that important but in times that stress can occur - powercut, new fish adding, other fish fighting etc etc... low numbers can kind of double the stress in this situation (i dont mean stress like we feel stress but its more like a panic or fear) and this can leave them susceptible to stress which can lead to diseases including those trace disease that do linger in most tanks (but usually starve off). I think with these being Madagascan as well its really important to get the same as a lot of Madagascan fish (and animals in general) are pretty uniquely evolved to survive.
Where abouts are you from maybe someone can help you find 6 or so more to add to the tank?
Hope that helps
Wills