I have two female micky mouse platies red and black ones. They became really fat, and I mean realy fat about 3 months ago. I thought they were pregnant but they never had babies. We recently began doing water changes due to nitrite levels being so high. Now one of the platies is skinny and the other looks so big it looks like its going to explode. Could they have been pregnant all this time and holding it? Or is something else wrong?