Late here, but my two cents. I had 3 females that grew up together and were in a 6X2' tank and previously, a 4X2' tank.
They got along great for years and then, they didn't. One became dominant and pushy and would instigate with the other two. At that point, I had the space, so I put each in a 3X2' (one being the original 6X2' split in half with a divider and separate heating elements).
Remember, separate is fine, but together can work or may not work, and even if it works for some time, that can change.
I was told females can cohabitate (see above), but males never should. I think you know this, but I am clarifying for others who might read this.