Minnow Behaviour.

[Gen]

Hi,

I have 6 little Mountain Minnows in my 60l tank. so far they are the only fish in there. At the moment they tend to split in to 2 groups of 3. One set seems to like slowly meandering around the plants, but the others like to swim flat out doing laps round the edge of the tank. Is this normal? Is this male/female behaviour? Is it going to change when I put a few more fish in the tank?

Thanks