Hello, I own a 5 gallon aquarium. I have had it for around 3 months.I do everything I am supposed to do to keep the fish alive and happy. However, today 2 of the 4 fish died. All fish are livebearers and they aren't aggressive towards each other. One was a young Swordtail and one was a Variutus Platy. These fish are the 2 slim fish of the aquarium. Would that have anything to do with there death? They were both inactive on the ground today not doing anything besides swimming up to eat. Also, I don't think it was an Ammonia spike or a Nitrite spike because the other fish have not done anything strange today. I am just curious and would like to know possible reasons of these deaths. (the swordtail died first then the platy later) Anything will be appreciated. I do not own a test kit to check the levels either.