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I can't help you there, but I can tell you when I first got mine the male did this and I was very concerned for him. I ran down on maybe the 3rd day in the morning to check on him and the female was dead and he was fine. Very weird as she showed no signs of anything whatsoever. Shortly later my other male swordtail did the same thing - started moping around and hiding, laying on bottom and then died. Since then the male and female I have left have been fine. I assumed the pet store gave me some sick fish. Not sure. Sad. Good luck. I hope you can save them.