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Discussion Starter · #1 ·
Anyone out there have experience with breeding Mollies?
This is the second time I've had at least one parent die after giving birth.
First time was a brackish tank, and both adults died within a day of the fry. All of the fry survived, although it was a small clutch (9, minus any that were eaten immediately by their parents.) I traded most in to an LFS a couple months later, but kept one young lady, and found her a new partner a month later. I actually thought they were both girls.
The pair moved into my saltwater tank about a month ago and recently moved into my 80g when I expanded. They have been happily gambolling about ever since. The two have not been gambolling exclusively together for a couple days, and have always spent about half their time in the open and half in the caves. I've never seen them get real cozy.
Today, I find the larger against the power head, not quite dead but appearing likely to be so soon. I also found at least ten miniatures in the tank, either born big or having been there a few days, likely coincidental with the 'taking space' phase. Closer inspection shows the decedent as clearly male. My little girl hardly seems big enough to have birthed this brood, but I know it wasn't the royal gramma or the peppermint shrimp, and no one else is remotely big enough (or black enough).
I've seen a variety of comments that suggest mollies are a bit prone to dying after giving birth, but can find no reason why this should be so, or why it should be the male, who is twice the size of mamma, and still slightly bigger than the gramma, who even hangs out with them now and then.
No sign of parasites or direct trauma. Perhaps a bit of bruising where he'd been against the power head for who knows how long.
The pups have mostly swum through the gates into the onboard refugium, where they can't become lunch and should still find plenty to eat, although I won't like getting them out of there.
Params are good, but for those who want to verify: pH is 8.2, temp is 80F, Amm is < .25, trites and trates are zero, phosphates are also present but barely, and Calc is ~420ppm. Just had a water change three days ago. Sal is 1.025.

Anyway, with no prior signs of aggression, is mamma likely to have beat him to death- she was rather young to be a mother? Trying to avoid child support? Worn out from trying to catch children in too big of a tank? Is mamma going to succumb like her parents did?

18,762 Posts
I have lots of experience with livebearers, including molly.

Death after giving birth happens pretty often with older females and sometimes with younger depending on conditions. The first thing to do that really prevents this is to have at least 4 females per male. Breeding is exhausting for the female and if she's the only one she isn't left alone. The male will often try to mate right away after she gives birth. Of course she's worn out.

The other thing that I find helps is to use a breeding net or container. Once the female is close to giving birth you can place her in it. That way after she gives birth she has a stress free place to rest where the male cannot get to her.
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