The fact is in the wild schooling fish like tetras occur in the 100s not 6 or 10 or 20. Somebody made up the number 6 as being the minimum. To really see schooling you need biggers groups and then some form of perceived threat since schooling is a defensive behavior. The threat can not be too great or the result in a tank is hiding not schooling.
I would suggest that to really see schooling one needs tetras or other schoolers in the dozens not the single or low double digits. This means you also should have an appropriately large enough tank.
I would suggest that to really see schooling one needs tetras or other schoolers in the dozens not the single or low double digits. This means you also should have an appropriately large enough tank.