Re: NANFA-- Questions about Heterandria formosa.....

Bob Bock (bockhouse_at_earthlink.net)
Sat, 21 Jun 2003 13:41:10 -0400

A couple of years ago, I brought a healthy gambusia female home from a
Florida trip and put her in a backyard tub with sailfin mollies over the
summer. By summer's end, I had at least 50 babies. They're known for
"super fetation" having a whole batch of fry incubating inside the mother,
all at different stages of development. the female gives birth every few
days. I don't know how long they can go without insemination before giving
birth, but I know that it's awhile.
----- Original Message -----
From: "unclescott" <unclescott_at_prodigy.net>
To: <nanfa_at_aquaria.net>
Cc: <livebearers_at_aquaria.net>
Sent: Saturday, June 21, 2003 11:03 AM
Subject: Re: NANFA-- Questions about Heterandria formosa.....

> > Are female H. formosa able to store sperm like other Poeciliids for
> continuous fertilization of eggs or do they require insemination for each
> egg(s)? Considering their differing way of gestation of their eggs and
> delivery mode I was curious if they differed in this aspect as well.
>
> >I have a group of 52 females from one local population whom I have
isolated
> in a 40 gallon tank away from any males. Females who were previously
> pregnant who have delivered their young do not seem to be gestating any
more
> young after a period of about five weeks.
>
> If you keep them in the middle 70s F (even though they can go a lot
cooler,
> gestation slows wayyyy down), give them lots of vegetation to hide in and
> lots of meaty food (rinsed, formerly frozen bloodworms, among other things
> work well), in time you should have a bunch of fry.
>
> Given the number of fish, I think you are wise to keep them in a 40 gallon
> tank. Too often aquarists see a small fish and think "small tank." Their
> behaviors are more natural and they are likely to be healthier in quarters
> where they have "room to rumble."
>
> A Copeia article several years ago singled out Het. formosa as one of the
> most -advanced? sophisticated? unique? - of the poeciliids practicing
> superfoetation. Because they are so small (and their fry relatively
large),
> a female would only have one or two full term fry in her body at a time.
But
> researchers found quite a series of really tiny eggs ready to go. The
> increase in size of the embryo (my memory is straining here) was somewhere
> in the neighborhood of 800-1000% ! Clearly there is nurturing from the
> female.
>
> One could form the image of quite an assembly line. In our age of extreme
> sports, now we have extreme procreation. ;) A remarkable little fish.
>
> All the best,
>
> Scott

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/ For more information about NANFA, visit our web page, http://www.nanfa.org