VISITOR'S QUESTIONS
14... Pregnant Swordtail
I'm happy to hear that my advice has been of help to
you, congratulations with your Red Sail-Fin Molly and Guppy fry, this
is a good indication that your care and aquarium conditions are in good
order. You have done the right thing by removing the gravid females
to a separate spawning tank, which of course should have some kind of
trap installed so that the fry, when born, will not be eaten by the
adults.
However, to answer your question, eggs are fertilised
in the ovarian cavity where they develop exclusively on their yolk until
they are ready for birth, (they do not receive nourishment from the
mother) this can take between 28 and 40 days depending on species and
climatic conditions. Unfortunately I have no knowledge of when your
females became pregnant, so you will need to work that out yourself,
I do know that they have been separated from the main aquarium for 10
days, as you told me.
If they had just been inseminated at that time, i.e..
just 10 days pregnant now, then you still have a good few days to wait
yet. Sometimes, shortly before birth, the eyes of the unborn fry can
be seen through the thin peritoneum (gravid spot) wall. If this is their
first brood it will probably be very small, perhaps just two or three
fry, however numbers will increase with each brood, the fourth usually
the largest, after that numbers will decrease again.
Finally, remember to provide shelter for the fry for
when they are born, usually with plants. When the fry are all released
from the female she must be removed, this should be to an aquarium with
quiet surroundings where she can recover.
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