Anyway, I knew something was up when one of the platies was darting around, swimming sideways, upsidedown, and at times it was crashing to the ground. I'm pretty sure this was the same one that was sitting at the surface the day before, getting air (even after the water change). It was also huge - big swollen belly that makes me wonder if it was carrying some fry. Which is odd, since I thought I had all females, and they've been in there 4 weeks! Definitely wasn't eating too much, I hardly feed them. I found it stuck to the powerfilter intake tube just a few minutes after I knew it was still alive, and got it out quick. Poor thing. It had what looked like a blood blister under the skin, smaller than it's eye, on it's belly. Don't know if that was from the filter suction or what.
So, now I only have 2 small fish cycling a 37 gallon. I don't know if I should add some hardy zebras or wait until it finishes cycling (whenever that will be). Any ideas or suggestions?