My mollies are dying!!

[Genral72]

I Had three mollies and all have died in the past three weeks.
The first to go became extremely fat did not notice a gravid spot so I don't think it was pregnant it died shortly later.
The second Paled a little its eyes shrunk then one eye grew back to normal size :huh:
The last to go Just died suddenly It was doing great then when I got up this morning it was dead. I noticed a brown spot that was not there the day before. The brown spot was on the side
I do 20% water changes twice a week. My ammonia is at 0 as is my nitrite. I don't know what my nitrate is. Ph is 6.9. GH 50ppm, KH 25ppm. This has not affected my other fish at all. :huh:
Oh well I didn't really like the mollies but I don't want this to spread to my other fish and I want to prevent this from happening again.

 

[Galaxie]

A brown spot? Did the cichlids attack them? Even those small cichlids are considered semi-aggressive. Mollys and neons may both have a short lifespan around them.

How long were the mollies in the tank before they died?
How long has the tank be running?
What sort of filter do you use? (gallons per hour?)
What is the water temperature?

 

[Genral72]

The brown spot was just that a brown spot. The cichlids are only about 2 inches long and I din't find any signs of agression such as nipped fins or blood.
The mollies were about 3-3.5 inches. The tank was has been running for either 2 or three years( not sure When I got it). I use a whispher triad 1000 power filter I don't know how many gallons per hour it is(my oarets gave it as a christmas gift and They bought it used They didn't ask the guy and I haven't been able to find any imformation on it). The tempature was 78 degrees.
Thanks for your help

 

[florit0274]

Not quite sure how relevant this is, but this is something I thought I would add. Many mollies prefer brackish water conditions. Although some may or may not do well in freshwater, from what I hear some species just never do well in freshwater.

I am not sure which species prefer what but Im sure there are placing on the web that you could read up on this.

 

[Genral72]

I've read that they will do better in brackish conditions but I have never heard of them not doing well in freshwater becuase it is freshwater!

 

[mandimoron]

If the tank environment is two or three years old, were the mollies of the same age? Because that's getting towards the end of their life expectancy, isn't it? And I personally think the brackish-or-bust thing for mollies is a myth.

As for the one that got really fat before dying, maybe it was dropsy?

 

[Genral72]

Dropsy not familiar with it? As for there age it is really uknown I bought them from the fish store about six months before the incident. They were already full grown at that time.