One of my platys, who had about 25+ fry a little over 1 month ago, died last night. I did a artial water change on Saturday, tested the water and all seemed fine. The fry are all well in their net breeder, the other 2 adult females seem fine. When I got home the red wagtail was at the bottom of the tank and looked like she was breathing heavily. By nightfall, she died. Anyone know what could have caused it? She had no signs of ich, just looked like her belly was puffed up. I felt terrible. Please let me know your thoughts so the others won't die too.