Thanks, I will remember the point about the male platys.
About the fitler. I have some what limited space and because of the
hood of the tank, I have to hang the filter on the back of the tank
but I really want to hang it on the side. The water flow is also at a
better direction (as my tank is originally set up as a feng shui tank)
and right now, the filter flow water towards the door. This may not be
of any concern to some but if I am getting a new fitler, I'd like to
figure out how I can get the filter to hang on the side, or to get an
underwater one to eliminate the water flow problem entirely. But it
looks like the recommendations are not good!

Any other suggestions welcome!