I lost all my fish in my 55, just a tad pole is alive. I should've did a major water change last night, but my babies where in the church play and then my in laws were over. It had gotten real cold and my tank heater couldn't keep the water temp up and all my platies and my rubber nose died. well today I went to do a water change and everything was dead but my step daughters tadpole. Guess the ammonia level or something from the dieing fish.