Hi all, hopefully someone can give me some great advise. Here's the deal.
About 2 months ago I had a female silver molly who started out to be a high strung appearing healthy fish. She was being tormented by my juvinile male black molly, which was resolved by getting another female molly. All seemed well, until about a month later when the silver suddenly became lethargic. She had appeared to have gotten slightly fatter in that last month, which I thought was potentially pregnancy. Unfortunately, she passed away within 3 days of the onset of lethargy.
A month has passed since the silver female died. My other female molly never seemed affected and she appeared healthy. She did not get increased torment from the male even after the other female died. However, about two weeks ago I noticed that she appeared to be getting slightly fatter. I know she bred with the male, so I assumed she was pregnant and she did not show any adverse signs or increased stress. In fact she seemed very happy and healthy until about 2 days ago. She suddenly became lethargic and she passed away last night. (she was a mature lyretail dalmation)
I guess I'm confused why my female mollies are dying. They seem totally heathy for slightly over a month, then suddenly get lethargic and die. Both appeared to be potentially pregnant, unless the slow fattening was something else?
All my other fish are fine. The male molly has been in since the beginning and has never had any problems. My tank has a variety of guppies, 3 small neons, a small algaeatter, a variety of snails, and the male molly (used to have the two other female mollies-but obviously no longer). The tank is well cycled, 15 g, with a Tetra 20g filter. Ammonia is less than 0.02 ppm, pH ~7.0, temp 76-78 F.
Any help would be greatly appreciated. What ever is going on seems to only affect the female mollies.