In April I was gifted 6 platies for my 20 gallon. 2 males and 4 females. A month or so after I got them one of the females died unexpectedly. She appeared to be pregnant when she died and all of the other fish in the tank were fine. A couple months go by and I get to today. When I woke up this morning another female was dead and she also appeared to be pregnant. All of the other platies are fine including 2 babies who survived being eaten. Water parameters are good because I test my water and do weekly water changes to keep it safe. I got these fish from a teacher of mine who breeds them. I'm not sure if this is important but I have an 18 year old clown plecostomus in the tank too. If anyone has any idea what could be going on I'd love the help.