It could have had an effect Spishkey but I find that small temperature changes are good for my fish, not a problem. When it comes to my goodeids, they breed much better and look healthier when I let the tank temperatures just move with the room temperature. Most of them are fine down to below 15C so low room temperatures are not a problem for them the way it is for platies. I really don't know if the temperature got too low for fry but I have kept platies at temperatures almost that low without problems. When I was younger, we never had tank heaters so we used incandescent lighting to maintain our tank temperatures. That means that they got some heat when we were home to watch the tank and got no heat when we were out. The time a light was on was based on our judgment of what it would do to tank temperatures so plants were harder to work with back then. The point is that tank temperatures varied quite a bit but the fish always produced fry and seemed fairly healthy. I think the minimum that I ever allowed for swordtails, guppies or platies at the time was about 21C.
