Meanwhile, in one of my community tanks, this couple, which are rare blue marbles, has claimed the corner of the tank with the amazon plant as their own, and they've been defending it vigorously.
Males can also have a hump on their heads, which the females do not get.
In this photograph, the male is on the left and the female is on the right. They had been busy attending the amazon plant before they spotted me; then they came to the glass to see what I wanted.
They've been cleaning the leaves and perhaps within the next few weeks, they will lay their first group (or clutch) of eggs.
In this same tank, I may have two pregnant tetras. They give live birth so that will be a new experience for everybody!