Breeding Livebearing Fishes
Among all aquarium fishes, livebearers are the easiest to breed.
All that is needed is a male and a female, together in one
aquarium. After a series of movements alongside the female, darting,
forming S-shapes with his body and back-ups, the male will introduce
sperm into the female's reproductive tract with gonopodium. The
fertilisation itself is very quick the gonopodium is directed at the
vent then the sperm is forcibly directed at it.
Livebearing females contribute through their bloodstream depending on
the species. The degree of such contribution in varying species is
unknown, but possibly in no species is there the intimacy of contact
that develops through the placenta of mammals. No structure same with
the mammalian placenta (afterbirth) develops. All needed food is present
in the eggs and oxygen needs are met through diffusion from the
immediate environment of the developing egg in the female's reproductive
system. The reproduction is described wherein eggs are simply kept until
they are hatched and the young are released which is known as
ovoviviparity.
A female carrying developing young can be recognised by her girth and in
most cases, by the dark spot near the vent called the gravid spot.
Careful examination of this area will oftentimes reveal the eyes of the
enclosed young fish. A female about to deliver young may
undergo a change in body outline which becomes too obvious to
experienced aquarists.
The newly delivered young should be placed gently in an uninhabited
aquarium with dense planting of fine-leafed plants. Myriophyllum or
Cabomba is exceptional for this. Breeding traps which allow the young to
drop through slots that the mother cannot pass through are
available and it works quite well. A difference on this theme is a nylon
net bag that serves the same purpose. The newborn young can eat large
infusorians like rotifers, fine grade food from birth and baby brine
shrimps. A possibly large aquarium should be provided for the young
ones. Small tanks inhibit the growth rate and the size attained by fish.
It is best to place the female in the delivery tank a week or so before
young are expected to be delivered. The Mollies are particularly liable
to premature deliveries of fish which will not
survive if the mothers are handled too close to their due date.
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