BTW, I have my own feelings about "schooling" fish that many would probably disagree with.
Fish that tend to school do so out of pure instinct . Saying you need a certain amount stems from we like to watch them school.
Having just 3 or 4 they will usually do just fine and their primary instinct is to to eat and avoid predators .... and they will still have a couple of their kind
I just got a school of 5 neon tetras as I like to watch them school.
However I already had only three Zebra Danios and they basically hang out together Some of this can be viewed as Danios chasing each other but, it can also be viewed that it just how they school .... rather fast.
The Danios do not bother the Tetras at all , and the Tetras just ignore them
BTW I also recommend some Cory cats . They will scour the bottom for food without disturbing the substrate, are small, are peaceful and get along with other fish, are cute, and are great fun to watch.
Once you have a few you will never have a community tank without them again.
Corys are another schooling fish but just a pair of them do just fine..